Would it be feasible for your teeth to straighten?

With help: They will need help from an orthodontist, they will not get better alone, if you are missing teeth and they shifted you need to get the missing teeth replaced to hold the rest of them in a stable position.

Crowding: Regardless your age, yes you can :). If the malalignment is minor, you can just have, e.g. Inman aligner that can straighten it fast. It's removable so you can still floss your teeth. If the crowding is moderate to severe, you rather have a comprehensive orthodontic treatment.