Been wanting a secondary monitor for a Mac? It’s possible you already have one.

If your Mac is running macOS Catalina, you can now use your iPad as a secondary monitor with the new “Sidecar” feature. It’s ridiculously easy to set up wirelessly through AirPlay.

First, a few notes. Unlike with some existing third-party screen-sharing apps such as Air Display 3, you can really only use your fingers on the display for simple actions such as scrolling through text.
…
Read full post here:
https://www.macworld.com/article/3406837/how-to-use-sidecar-to-make-your-ipad-a-secondary-mac-display.html