Well there's basically no way to leave a typical modern passenger plane once it's in the air. The doors lock in the frame from the inside and once the cabin is pressurized the pressure difference between inside and outside makes them impossible to open.
Actually there is one way - some windows on the flight deck can be opened sometimes and apparently exiting a passenger plane at traveling speed is survivable.
There's the story of British Airways Flight 5390 where the flight deck experienced a explosive decompression due to a faulty cockpit window and the captain was ejected out of the window partially, his knees got caught on the flight controls while his upper body stuck out of the window. Unable to pull him back in flight attendants held onto his legs for 20 minutes until the First Officer was able to perform a emergency landing. The pilot survived with - for what he has endured - minor injuries, he returned to flying 5 months after the incident.
From what I read it was more that the First Officer was worried that his body might damage flight controls or engines if they let him go. Probably both.
There is a similar story from 2018 where a passenger was partially ejected from a damaged window after a critical engine failure. She got pulled back in by passengers and flight attendants but later succumbed to her injuries. Interestingly what killed her was blunt force trauma from being smashed against the outside of the cabin due to the violent nature of the explosive decompression, not the enviromental circumstances of being on the outside of a plane travelling at cruising height & speed.
Although your chances of surviving that for a prolonged time are slim at best I would say. Captain Lancaster was just very very lucky.