The passenger cabin can be accessed from the cockpit view using the arrow keys on your keyboard to move the camera UP/DOWN/LEFT/RIGHT. The camera can then be moved FORWARD/BACK by holding LEFT ALT and using the arrow keys. Pressing the "F" key will reset your camera back to the default pilot position. Alternatively, you can access several pre-set cabin camera positions using the MSFS Camera menu.

Users with an Xbox controller can press and hold LB followed moving the two thumbsticks to walk to and view the cabin.