easy... Singapore changi (t1-3) has that

T1-3, there's a common transit area. When you deplane, you get into the transit area. Can choose to go thru immigration, lounge, or transit for new plane

T4, there's no common area. After deplane, u have to go thru immigration or thru transit security. Not sure if u can easily go from t4 transit area back landside. You can always take shuttle between T4 airside to t1-3 airside (they allow you on shuttle as long as you have enough time to departure)


However, singapore is quite strict. people have entered transit area for tax-free goods or see famous people, tried to re-enter Singapore without flying, and jailed/fined. If you had some exception (flight cancelled/trip in vain), maybe they'll give you an exception. But it does answer your question (don't need escort between transit area and landside. Can take shower in lounge after landing, then enter Singapore, then go back airside to catch the next connection)