The passenger cabin can be accessed from the cockpit view using control assignments to move the camera around the aircraft. 

With a keyboard, use the arrow keys to move the camera UP/DOWN/LEFT/RIGHT. The camera can then be moved FORWARD/BACK by holding [LEFT ALT] and using the UP/DOWN arrow keys. Pressing the [F] key will reset the camera back to the default pilot position. 

With a PS5 controller, press and hold the [L1] button and use the thumbsticks to move your camera around the aircraft. Pressing the [R3] (right stick) button will reset the camera back to the default pilot position.

With an Xbox controller, press and hold the [LB] button and use the thumbsticks to move your camera around the aircraft. Pressing the [RS] (right stick) button will reset the camera back to the default pilot position.

A selection of preset camera positions for the cabin, cockpit and wing views are also available via the MSFS Camera menu. The MSFS Camera menu also includes a button to reset the camera position.