As @myflash2 mentioned, you can use an app in your PC and tablet to use it as a second monitor.
But I would recommend buying a second monitor. As long as you don’t go too big, you could get one at a decent price and it will be much bigger than a tablet and you will be overall happier having the bigger screen and being able to open several windows.
In my photo, I have ATC and the VFR map open in my left screen, its a 1980 x 1200, 24 inch, but you can get a 1920X1080 24 inch. Opening both screens in a tablet would look to small. Well at least it would be to me, being a senior citizen, my vision isn’t as good as it use to be.
But if you are younger and still have good vision, the tablet can be a great option.