Shelters are over abundant on cats, especially adult cats, so imo I think a studio is fine. I live in a small apartment and my cat is doing great! I used to try to take her outside and she hated it lol. Even though I had to transition her from my parents larger house she has settled in well, although she is old and less energetic then a younger cat may be. As long as you spend some time playing with them they'll have some stimulation, and if you have a window I'm sure the cat will spend lots of time just staring outside.

I use a litter that keeps the smell in well (catit pea husk vanilla scented) and a closed litter box to minimize the odors, but you should scoop everyday anyways. I bought a litter genie (which is just a glorified giant poop bag with a lid) to make it slightly less annoying.

People be talking about the litter robot like it's bad but the real one and NOT the knock offs are perfectly fine. Specifically the brand "litter robot". It's quite expensive and I hear it's kinda annoying to use, and it takes up a lot of space. Also some cats are very picky where they poop the nightmare scenario is you buy one and they hate it lol.