Litter box suggestions

I am about to adopt a middle aged fella and I live in a single room with communal bathroom and kitchen.

Im getting him a big cat tree but he has "low energy" so I think he would be alright in my room for the most part.

So for now im looking for a litter box that will keep the smell down as much as possible. Im still not 100% on getting him until im sure everything will work and he will be happy.

Thanks for any help