We’ve already looked at many of the multitasking features you’ll find in iPadOS, but one of the most useful may be the Mac-compatible Sidecar mode, which lets you use your Apple tablet as a secondary display.
What is Sidecar?
Available to Mac users who have iPads running the most current edition of the OS, Sidecar enables users to extend their Mac desktop by using their iPad as a second display or as a high-precision input device across creative Mac apps.
This works in both wired and wireless mode and is controlled via the Display menu.
Refer Here for Original Post and Source https://www.computerworld.com/article/3407616/how-to-use-your-ipad-as-a-second-mac-display-with-sidecar.html#tk.rss_all