If you leave passenger(s) in the Tesla Model Y and you take your phone the doors will automatically lock on exit (if enabled) and the vehicle alarm will be active. If a passenger opens a door this would set off the vehicle alarm.
Camp mode ensures that the doors of the Tesla Model Y do not lock when you leave. The Climate Control system will remain running and the infotainment screen remains powered on so the passengers can play games, listen to music or stream video content. Opening a door or window will not set off the vehicle alarm.