QtLocation geolocation plugins should use the associated QQmlEngine's QNetworkAccessManager

QQmlEngine has networkAcessManager(), networkAccessManagerFactory(), and setNetworkAccessManagerFactory(), which allow an application to proxy, filter, or entirely disable the QML engine's network access. From the documentation for networkAccessManager:

Returns a common QNetworkAccessManager which can be used by any QML type instantiated by this engine.

For normal QML elements,this makes it easy to create an engine-wide offline mode:

QQmlEngine *myEngine = qmlEngine(myItem);
myEngine->networkAccessManager()->setNetworkAccessible(QNetworkAccessManager::NotAccessible);

In comparison, many of the geolocation plugins relied on by the QtLocation QML types create their own private QNAM instances. Without an accessor API, some apparent solutions are application-wide filtering with a QNetworkProxy or QNetworkProxyFactory, or creating a Map with plugin parameters that specify an unreachable tile server. Neither option is graceful.