Yes, if the drone runs out of battery, it will automatically fly back to the starting point. This is the low battery return function (Low Battery RTH), which is initiated when the battery level is only sufficient for a safe return. You will receive a warning message in the DJI Fly app, and after 10 seconds the return will start if you do nothing. The function can be cancelled via the app or remote control, but then the battery may no longer be sufficient.