It's called spacedesk, and with it, I was able to quickly and easily use my tablet or my smartphone ... even do this to turn your old iPhone or iPad into a second monitor for your PC, too.

and then add your iPad as a second monitor in Display settings This article shows how to expand your Windows 11 desktop by ...

The program will also start the x0vncserver command. Press Ctrl+C to terminate the vnc server and turn off the virtual monitor. Start a vnc client on your android tablet - e.g. the android app bVBC - ...