Run xrandr
to identify your displays. Calculate virtual buffer. Setup displays with:
xrandr --output HDMI-2 --scale 2x2 --mode 1920x1080 --fb 3840x3760 --pos 0x0
xrandr --output eDP-1 --scale 1x1 --pos 640x2160
See https://backports.debian.org/.
sudo dpkg-reconfigure fontconfig-config
Choose autohinter, automatic subpixel rendering and no bitmapped fonts. Then:
sudo dpkg-reconfigure fontconfig
To apply the changes.