If craphic card does not allow big enough resolution, one way to manipulate screen is to scale screen size. At first need to know display port
xrandr | grep connected
Also screen size is good to know
xdpyinfo | grep -B2 resolution
If wanting a ”bigger resolution”, place your display output on the output section like VGA1
(in this computer is LVDS).
xrandr --output LVDS --scale 1.25x1.25
If wanting a ”smaller resolution” set a different value like –scale 0.75×0.75
xrandr --output LVDS --scale 0.75x0.75
To restore original size
xrandr --output LVDS --scale 1x1
Of course you can add the command to the startup applications or script