That ship has sailed. This behavior did not start at 18. If parents are still confidently in a position they feel they can "parent" (doubtful), then one option

That ship has sailed. This behavior did not start at 18. If parents are still confidently in a position they feel they can "parent" (doubtful), then one option is to create alternatives rather than mere restrictions, i.e. sign them up for extra-curriculars. Otherwise, unless this legal adult wants to change, they won't.