It concerns Auqaris BQ M10 FHD with nice 10" screen. I tried to use the trick: create file
Xft.dpi: 224 inside it (see xmir-setup on XDA).
This trick helps for Geany, Firefox, LibreOffice, but doesn't help for Djview4. Trick works with DPI for fonts, but doesn't for menu icons and pictures. An other way I know can found there, I didn't test it, because of necessary to made system part writable.
I think this problem is similar to HiDPI with Retina in Linux. In usual Linux we can try to use
Section "Monitor" Identifier "<default monitor>" Option "DPI" "224 x 224" EndSection
xorg.conf.d/90-monitor.conf or use
xrandr --dpi 224. But we have Libertine and I don't know how to solve this problem.