My laptop monitor is 1920x1080 15.6-inch FHD
I have a monitor with same characteristics and same problem (fonts and windows too small).
Changing the font dpi in Mate Tweak options does not completely solve the issue because the windows and program text did not scale together.
I ended up using xrandr --output eDP-1 --scale 1.5x1.5 and got good results
Using Ubuntu Mate 20.04, fresh install