I'm one person looking for an apartment, and I'm interested in this 2 bedroom apartment I found...?

It would be the landlord, not the tenant (you would become the tenant)

If you can afford it, there's no reason they shouldn't - but you might be asked why you need an extra room (often there are limits on people staying over, and you can't add extra tenants without permission)

I would imagine they only care if you can afford to pay for it. One person can get a 5 bedroom apartment if they can afford it.

I had a 2 RB apartment as a single. They should rent you any size apartment you can pay for.

Most landlords would be extremely pleased to under-occupy an apartment. Less people living there means less wear and tear for the same rental income.
I don't know why you would think it is a problem.

The tenant? You mean the landlord or property manager? They shouldn't care. Lots of individuals rent 2 bedroom apartments. If you're getting section 8 subsidy though, you won't be able to have it

The owner just wants the rent. They don't care how many people live there.

Monly talks