At what altitude? At low altitude, it is theoretically possible (although some passenger aircrafts have a lock).

But even then it would still require significant strength, as there would likely be some air differential due to the aircraft's speed/air pressure against the door.

At higher altitudes it is essentially impossible for a human. You'd have to blow apart the door or equivalent.

The biggest thing is the pressure differential. And that varies based on speed/altitude/etc. At normal cruise in a jet aircraft, it just isn't happening.