Widget::Widget(QWidget *parent) : QWidget(parent), ui(new Ui::Widget)
{
    ui->setupUi(this);

    QBitmap cursorb(16, 16);
    cursorb.clear();
    {
    QPainter cpainter(&cursorb);
    cpainter.setPen(Qt::color1);
    cpainter.drawLine(7, 0,  7, 14);
    cpainter.drawLine(0, 7, 14,  7);
    }

    QCursor m_plotCursor = QCursor(cursorb, cursorb, 7, 7);

    setCursor(m_plotCursor);
}

QApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

static HCURSOR createBitmapCursor(const QCursor &cursor, qreal scaleFactor = 1)
{
 .....

if (!qFuzzyCompare(scaleFactor, 1)) {
        const QSize scaledSize = (QSizeF(bbits.size()) * scaleFactor).toSize();
        bbits = bbits.scaled(scaledSize, Qt::KeepAspectRatio, Qt::SmoothTransformation);
        mbits = mbits.scaled(scaledSize, Qt::KeepAspectRatio, Qt::SmoothTransformation);
    }

...
}