This is an interesting question, with a generic answer. Basically it depends on the aircraft model. Some cockpits are rather small and space is indeed limited. So you must indeed be careful when seating yourself in the pilot/copilot seat. The seat assembly does slide forward and aft providing easier means of entry and exit. The head room is also limited as well. So you might need to bend your upper body, and outstrech your leg when seating yourself in the seat.