If there isn't a passenger viewpoint on the plane's configuration you can move your viewpoint from pilot's view backwards into the fusalage by adjusting the z-offset-m value. Then adjust x-offset-m to move sideways into a window passenger seat, then adjust y-offset-m to raise or lower your height. Then turn your view by adjusting PanView Dir left or right to look out of the window. You may be disappointed to find some planes don't have a well modelled interior, maybe no seats and sometimes no fusalage sides, so you end up in the fresh air surrounded by bits and pieces of wings and landing gear and other aircraft parts. Very interesting for those who like flying the plane from unusual positions!
The B1900 has seats fitted. Some planes do, some planes don't!
This C47 built by the French PAF lads has nice passenger seats.
fast forward the video to 52 seconds about a quarter along the timeline.