Configure "-help" does not mention "-xplatform"

>configure --help

Usage:  configure [options] [-- cmake-options]

This is a convenience script for configuring Qt with CMake.
Options after the double dash are directly passed to CMake.

Top-level installation directories:
  -prefix <dir> ...... The deployment directory, as seen on the target device.
                       [/usr/local/Qt-$QT_VERSION; qtbase build directory if
                       -developer-build]
  -extprefix <dir> ... The installation directory, as seen on the host machine.
                       [SYSROOT/PREFIX]
  -external-hostbindir <path> ... Path to Qt tools built for this machine.
                       This option is required when cross-compiling Qt.

Fine tuning of installation directory layout. Note that all directories
except -sysconfdir should be located under -prefix:

  -bindir <dir> ......... Executables [PREFIX/bin]
  -headerdir <dir> ...... Header files [PREFIX/include]
  -libdir <dir> ......... Libraries [PREFIX/lib]
  -archdatadir <dir> .... Arch-dependent data [PREFIX]
  -plugindir <dir> ...... Plugins [ARCHDATADIR/plugins]
  -libexecdir <dir> ..... Helper programs [ARCHDATADIR/bin on Windows,
                          ARCHDATADIR/libexec otherwise]
  -qmldir <dir> ......... QML imports [ARCHDATADIR/qml]
  -datadir <dir> ........ Arch-independent data [PREFIX]
  -docdir <dir> ......... Documentation [DATADIR/doc]
  -translationdir <dir> . Translations [DATADIR/translations]
  -sysconfdir <dir> ..... Settings used by Qt programs [PREFIX/etc/xdg]
  -examplesdir <dir> .... Examples [PREFIX/examples]
  -testsdir <dir> ....... Tests [PREFIX/tests]
  -hostdatadir <dir> .... Data used by qmake [PREFIX]

Conventions for the remaining options: When an option's description is
followed by a list of values in brackets, the interpretation is as follows:
'yes' represents the bare option; all other values are possible prefixes to
the option, e.g., -no-gui. Alternatively, the value can be assigned, e.g.,
--gui=yes. Values are listed in the order they are tried if not specified;
'auto' is a shorthand for 'yes/no'. Solitary 'yes' and 'no' represent binary
options without auto-detection.

Configure meta:

  -help, -h ............ Display this help screen
  -redo ................ Re-configure with previously used options.
                         Additional options may be passed, but will not be
                         saved for later use by -redo.

  -feature-<feature> ... Enable <feature>
  -no-feature-<feature>  Disable <feature> [none]
  -list-features ....... List available features. Note that some features
                         have dedicated command line options as well.

Build options:

  -cmake-generator <name> ... Explicitly specify the build system generator for
                         CMake instead of auto-detecting one.
  -cmake-use-default-generator ... Turn off auto-detection of the CMake build
                         system generator.
  -no-guess-compiler ... Do not guess the compiler from the target mkspec.
  -release ............. Build Qt with debugging turned off [yes]
  -debug ............... Build Qt with debugging turned on [no]
  -debug-and-release ... Build two versions of Qt, with and without
                         debugging turned on [yes] (Apple and Windows only)
  -optimize-debug ...... Enable debug-friendly optimizations in debug builds
                         [auto] (Not supported with MSVC or Clang toolchains)
  -optimize-size ....... Optimize release builds for size instead of speed [no]
  -force-debug-info .... Create symbol files for release builds [no]
  -separate-debug-info . Split off debug information to separate files [no]
  -gdb-index ........... Index the debug info to speed up GDB
                         [no; auto if -developer-build with debug info]
  -gc-binaries ......... Place each function or data item into its own section
                         and enable linker garbage collection of unused
                         sections. [auto for static builds, otherwise no]
  -force-asserts ....... Enable Q_ASSERT even in release builds [no]
  -developer-build ..... Compile and link Qt for developing Qt itself
                         (exports for auto-tests, extra checks, etc.) [no]

  -shared .............. Build shared Qt libraries [yes] (no for UIKit)
  -static .............. Build static Qt libraries [no] (yes for UIKit)
  -framework ........... Build Qt framework bundles [yes] (Apple only)

  -platform <target> ... Select mkspec for the qmake companion files
  -device <name> ....... Select devices/mkspec for the qmake companion files
  -device-option <key=value> ... Add option for the device mkspec

  -appstore-compliant .. Disable code that is not allowed in platform app stores.
                         This is on by default for platforms which require distribution
                         through an app store by default, in particular Android,
                         iOS, tvOS, and watchOS. [auto]

  -qt-host-path <path> . Specify path to a Qt host build for cross-compiling.
  -qtnamespace <name> .. Wrap all Qt library code in 'namespace <name> {...}'.
  -qtlibinfix <infix> .. Rename all libQt6*.so to libQt6*<infix>.so.

  -testcocoon .......... Instrument with the TestCocoon code coverage tool [no]
  -gcov ................ Instrument with the GCov code coverage tool [no]

  -trace [backend] ..... Enable instrumentation with tracepoints.
                         Currently supported backends are 'etw' (Windows) and
                         'lttng' (Linux), or 'yes' for auto-detection. [no]

  -sanitize {address|thread|memory|fuzzer-no-link|undefined}
                         Instrument with the specified compiler sanitizer.
                         Note that some sanitizers cannot be combined;
                         for example, -sanitize address cannot be combined with
                         -sanitize thread.

  -coverage {trace-pc-guard|source-based}
                         Specify the 'trace-pc-guard' coverage instrumentation for
                         sanitizers or generate instrumented code to collect execution
                         counts and enable code coverage analysis, respectively. (Clang only)

  -c++std <edition> .... Select C++ standard <edition> [c++20/c++17/c++14/c++11]

  -sse2 ................ Use SSE2 instructions [auto]
  -sse3/-ssse3/-sse4.1/-sse4.2/-avx/-avx2/-avx512
                         Enable use of particular x86 instructions [auto]
                         Enabled ones are still subject to runtime detection.
  -mips_dsp/-mips_dspr2  Use MIPS DSP/rev2 instructions [auto]

  -qreal <type> ........ typedef qreal to the specified type. [double]
                         Note: this affects binary compatibility.

  -R <string> .......... Add an explicit runtime library path to the Qt
                         libraries. Supports paths relative to LIBDIR.
  -rpath ............... Link Qt libraries and executables using the library
                         install path as a runtime library path. Similar to
                         -R LIBDIR. On Apple platforms, disabling this implies
                         using absolute install names (based in LIBDIR) for
                         dynamic libraries and frameworks. [auto]

  -reduce-exports ...... Reduce amount of exported symbols [auto]
  -reduce-relocations .. Reduce amount of relocations [auto] (Unix only)

  -plugin-manifests .... Embed manifests into plugins [no] (Windows only)
  -static-runtime ...... With -static, use static runtime [no] (Windows only)

  -pch ................. Use precompiled headers [auto]
  -ltcg ................ Use Link Time Code Generation [no]
  -linker [bfd,gold,lld] Force use of the GNU ld, GNU gold or LLVM/LLD linker
                         instead of default one (GCC only)
  -ccache .............. Use the ccache compiler cache [no] (Unix only)

  -warnings-are-errors . Treat warnings as errors [no; yes if -developer-build]

Build environment:

  -sysroot <dir> ....... Set <dir> as the target sysroot

  -pkg-config .......... Use pkg-config [auto] (Unix only)

  -D <string> .......... Pass additional preprocessor define
  -I <string> .......... Pass additional include path
  -L <string> .......... Pass additional library path
  -F <string> .......... Pass additional framework path (Apple only)

  -sdk <sdk> ........... Build Qt using Apple provided SDK <sdk>. The argument
                         should be one of the available SDKs as listed by
                         'xcodebuild -showsdks'.

  -android-sdk path .... Set Android SDK root path [$ANDROID_SDK_ROOT]
  -android-ndk path .... Set Android NDK root path [$ANDROID_NDK_ROOT]
  -android-ndk-platform  Set Android platform
  -android-abis .......  Only one ABI can be specified, default is: armeabi-v7a
  -android-javac-target  Set the javac build target version [8]
  -android-javac-source  Set the javac build source version [8]
  -android-style-assets  Automatically extract style assets from the device at
                         run time. This option makes the Android style behave
                         correctly, but also makes the Android platform plugin
                         incompatible with the LGPL2.1. [yes]

Component selection:

  -skip <repo> ......... Exclude an entire repository from the build.
  -make <part> ......... Add <part> to the list of parts to be built.
                         Specifying this option clears the default list first.
                         [libs and examples, also tools if not cross-building,
                         also tests if -developer-build]
  -nomake <part> ....... Exclude <part> from the list of parts to be built.
  -gui ................. Build the Qt GUI module and dependencies [yes]
  -widgets ............. Build the Qt Widgets module and dependencies [yes]
  -no-dbus ............. Do not build the Qt D-Bus module
                         [default on Android and Windows]
  -dbus-linked ......... Build Qt D-Bus and link to libdbus-1 [auto]
  -dbus-runtime ........ Build Qt D-Bus and dynamically load libdbus-1 [no]
  -accessibility ....... Enable accessibility support [yes]
                         Note: Disabling accessibility is not recommended.

Qt comes with bundled copies of some 3rd party libraries. These are used
by default if auto-detection of the respective system library fails.

Core options:

  -doubleconversion .... Select used double conversion library [system/qt/no]
                         No implies use of sscanf_l and snprintf_l (imprecise).
  -glib ................ Enable Glib support [no; auto on Unix]
  -eventfd ............. Enable eventfd support
  -inotify ............. Enable inotify support
  -icu ................. Enable ICU support [auto]
  -pcre ................ Select used libpcre2 [system/qt/no]
  -zlib ................ Select used zlib [system/qt]

  Logging backends:
    -journald .......... Enable journald support [no] (Unix only)
    -syslog ............ Enable syslog support [no] (Unix only)
    -slog2 ............. Enable slog2 support [auto] (QNX only)

Network options:

  -ssl ................. Enable either SSL support method [auto]
  -no-openssl .......... Do not use OpenSSL [default on Apple]
  -openssl-linked ...... Use OpenSSL and link to libssl [no]
  -openssl-runtime ..... Use OpenSSL and dynamically load libssl [auto]
  -schannel ............ Use Secure Channel [no] (Windows only)
  -securetransport ..... Use SecureTransport [auto] (Apple only)

  -sctp ................ Enable SCTP support [no]

  -libproxy ............ Enable use of libproxy [no]
  -system-proxies ...... Use system network proxies by default [yes]

Gui, printing, widget options:

  -cups ................ Enable CUPS support [auto] (Unix only)

  -fontconfig .......... Enable Fontconfig support [auto] (Unix only)
  -freetype ............ Select used FreeType [system/qt/no]
  -harfbuzz ............ Select used HarfBuzz-NG [system/qt/no]
                         (Not auto-detected on Apple and Windows)

  -gtk ................. Enable GTK platform theme support [auto]

  -no-opengl ........... Disable OpenGL support
  -opengl <api> ........ Enable OpenGL support. Supported APIs:
                         es2, desktop (default on Unix),
                         dynamic (Windows only, default on Windows)
  -opengles3 ........... Enable OpenGL ES 3.x support instead of ES 2.x [auto]
  -egl ................. Enable EGL support [auto]

  -qpa <name> .......... Select default QPA backend(s) (e.g., xcb, cocoa, windows)
                         A prioritized list separated by semi-colons.
  -xcb-xlib............. Enable Xcb-Xlib support [auto]

  Platform backends:
    -direct2d .......... Enable Direct2D support [auto] (Windows only)
    -directfb .......... Enable DirectFB support [no] (Unix only)
    -eglfs ............. Enable EGLFS support [auto; no on Android and Windows]
    -gbm ............... Enable backends for GBM [auto] (Linux only)
    -kms ............... Enable backends for KMS [auto] (Linux only)
    -linuxfb ........... Enable Linux Framebuffer support [auto] (Linux only)
    -xcb ............... Enable X11 support [auto] (Linux only)

  Input backends:
    -libudev............ Enable udev support [auto]
    -evdev ............. Enable evdev support [auto]
    -libinput .......... Enable libinput support [auto]
    -mtdev ............. Enable mtdev support [auto]
    -tslib ............. Enable tslib support [auto]
    -bundled-xcb-xinput  Use bundled XInput2 support [auto]
    -xkbcommon ......... Enable key mapping support [auto]

  Image formats:
    -gif ............... Enable reading support for GIF [auto]
    -ico ............... Enable support for ICO [yes]
    -libpng ............ Select used libpng [system/qt/no]
    -libjpeg ........... Select used libjpeg [system/qt/no]

Database options:

  -sql-<driver> ........ Enable SQL <driver> plugin. Supported drivers:
                         db2 ibase mysql oci odbc psql sqlite
                         [all auto]
  -sqlite .............. Select used sqlite [system/qt]