While there are several solutions to use a tablet as a second display for your PC, most are paid, and many of the free ones have limitations and don’t provide the best user experience ...

Duet Display lets you use any Android device as a second screen for your Mac, whether wired or wireless, giving you extra space for multitasking.

I also have a S9 ultra tablet that is wireless to the same router. Can I use my S9 tablet as a second monitor? Or does my desktop have to be connected wirelessly also for this to work? Thanks!

Or you can flip the second screen so that it’s back-to-back with the primary display, allowing you to either fold the screen down over the keyboard for use in tablet mode.