Adjust Screen Brightness Ubuntu 19.10 - 22.04

Terminal: xrandr -q | grep " connected"
Output: eDP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 309mm x 173mm

So my connected screen name is eDP-1

xrandr --output eDP-1 --brightness 0.5

0.5 = 50% of current brightness. Back to normal use:

xrandr --output eDP-1 --brightness 1

brightness 1 = 100%

Source and thanks to https://askubuntu.com/questions/149054/how-to-change-lcd-brightness-fro…