Qt

https://en.wikipedia.org/wiki/Qt_(software)

Main

DPI

QT_SCALE_FACTOR [numeric] defines a global scale factor for the whole application, including point-sized fonts

QT_SCALE_FACTOR=2

QT_AUTO_SCREEN_SCALE_FACTOR [boolean] enables automatic scaling, based on the monitor’s pixel density. This won’t change the size of point-sized fonts, since point is a physical measurement unit. Multiple screens may get different scale factors.

QT_AUTO_SCREEN_SCALE_FACTOR=1

QT_SCREEN_SCALE_FACTORS [list] specifies scale factors for each screen. This won’t change the size of point-sized fonts. The environment variable is mainly useful for debugging, or to work around monitors with wrong EDID information(Extended Display Identification Data).

QT_SCREEN_SCALE_FACTORS=1.5
QT_SCREEN_SCALE_FACTORS="2;2"

https://doc.qt.io/qt-5/highdpi.html