Auto size android
How to make a QPushButton is android's largest auto or adjusted
You need to scale the button size like Android apps do. I think you mean that, right?
you can use the screen DPI value to scale your app in a device independent manner if you want that. e.g. with "QScreen::physicalDotsPerInch":http://qt-project.org/doc/qt-5/qscreen.html#physicalDotsPerInch-prop