xrandr is a command-line utility for connecting to an external monitor or projector. I use it because I don’t have a GUI option for connecting to a projector on my machine.
xrandr - This command lists all connected displays. Once you know which display is connected, you can connect to it using
xrandr.
xrandr --output DPI --auto --autoscales the resolution automatically. You can also set your own resolution, as long as it’s supported by the monitor or projector.
xrandr --output DP1 --mode 1920x1080 For custom resolution.