Not necessarily. Depending on the setup bought by the airline You travel on, there may well be a rear airstair installed on the aircraft. It is stowed behind the door (viewed in direction of flight, facing the door from the inside, it is on the right) and can be pulled and folded out if desired.
This stair speeds up boarding and disembarkation noticeably but is not exactly popular with the cabin attendants staffing the exit: it is rather heavy and not that easy to retract and restow after use. Also, some airfields do not like its use, typically because they have no equipment or staff to keep the passengers from wandering below the wing and through the propeller arc.
We use this stair every time we are allowed to and if the passenger number is above 40. With less passengers, experience shows that the rear stair is usually ignored. Most passengers seem to prefer standing out in the rain at the forward entry to quickly boarding a well tempered cabin in the back even with the rear flight attendant waving, calling or using whatever other means to attract their attention...