Solution I use (works with _most_ apps -- GTK/Qt/WxWidgets/Electron, custom opengl/sdl apps are the main problem)
Go to window scaling and set it to 2x, this will cause the compositor to zoom in to each window 2x. Now everything will look obnoxiously big.
Then, go to the display settings, and set the display scaling to 1.5x or 1.7 or whatever it is that works for your DPI. (confusingly, this means zoom out)
So the zoom in/zoom out "cancel out" and you get a good balance.
Of course, it is rendering to a larger zoomed out canvas uselessly, but in modern CPU/GPU this doesn't cause too much of an extra hit on battery life.
This solution also has the benefit that if you use multiple different displays, you can as needed set different display "zoom out" levels for each one, and have it look good on both.
Where this falls over:
- OpenGL/custom SDL apps like I said before that don't respect your scale factor.
- Non Hi-DPI GTK themes (there are many hidpi ones available though)
You set the QT_SCALE_FACTOR env var for QT apps to also follow this, btw.
