It is very easy to scale MATLAB 2018b with the DisplayScaleFactor variable.This works very fine for nearly all systems and applications.
But since 2019b this variable is no longer working for simulink. Simulink is now redesigned and this variable has nolonger an effect on scaling of simulink.
The text and buttons are too small to read and work with them efficiently.
The allready known workarounds do not work.
My working system :
openSUSE Leap 15.1 64-bit with KDE
All updates for system and MATLAB installed