Is it possible to limit macbook display resolution/size for part of the screen?
Yes, I would recommend using SwitchResX to find a resolution that works for you:
https://www.madrau.com/
Note that you will have to live with the fact that the displayed area is in the center of the display, thus if you want to "block" a part of the right hand side of the display, you'll also have to block a part of the left hand side of the display of the same size.