A rental closet is almost always the same closet: a single hanging rail, one high shelf, and a door that does not quite clear the carpet. You cannot rebuild it and you should not try.
What you can do is use the space that the rail leaves empty, which in most closets is more than half of it.
The dead air under short garments
Shirts and jackets occupy the top metre of a closet. Below that is nothing at all, and that is the largest unused volume in a small bedroom.
A hanging shelf organizer fills it with six folded-clothes shelves and hangs from the rail you already have. No tools, nothing in a wall, and it comes down with you when you move. It is the single highest-return thing on this page.
The space under the bed
Under-bed storage usually fails because the gap is a few centimetres too shallow for any box worth owning. Raising the bed fixes that in about five minutes.
Adjustable risers stack to three, five or eight inches, so you choose the gap rather than accepting it. Measure the boxes you already have first and set the height to those, rather than raising the bed as far as it goes and living with a bed you have to climb into.
Drawers where everything migrates
Without dividers a drawer is one bin, and folded clothes unfold themselves within a week. Splitting a drawer into sections is what makes folding stick.
The SpaceAid bamboo dividers are spring-loaded, so they hold against the drawer sides with no screws and no adhesive, which is the whole point in a rental. For the small things a divider alone will not contain, the Canfanni tray set gives you thirteen trays in three sizes to arrange inside those sections.
The order that works
Closet first, then drawers, then under the bed. The closet gives you somewhere to put the things you find in the drawers, and the under-bed boxes are for the seasonal things you should not be storing at eye level anyway.