Set Camera to UI bound?

Yeah it’s an emulator and i’d like to recreate a similar look. I asked gemini and it told me that using texture with a scene capture reduce perfomances. Since I want to run this on mobile I’d like to optimize it as much as I can. There’s no way I can force to render camera at a particular size and only in a portion of the screen? Idk using coordinates and giving it width and height through c++?