This post led me to this solution:
xrandr --listmonitors to learn the name of your monitor. Mine is “None-1”
Output:
Monitors: 1
0: +*None-1 1280/339x480/127+0+0 None-1
Then scale the screen with xrandr --output None-1 --scale 1.5
When you want to go back to normal use xrandr --output None-1 --scale 1