Wide body aircraft have two unit load device on main fwd and aft cargo door and luggage loader on bulk cargo door.
A320s have two cargo door FWD and AFT and one of them may be used for unit load device or both of them will be luggage loading. The bulk cargo door which is the third is probably never used.
Freighter aircraft has 3 cargo doors. A Boeing 747 have a nose cargo door as seen here:
But in FS2020, there is only one catering truck in one of the aircraft right side door and one baggage ramp in one of the cargo door.