In the model 3 at least, the rear doors can also be opened without power by pulling a cable. Not as obvious as the front doors, I'll say, but you will be able to get out.
I don't know what you want me to say, my 2019 Model 3 has a manual door release handle on top of the panel inside the door of the back seat? Maybe it's a EU regulation thing.
Also mine looks nothing like the manual posted. Just to point out, this wasn't a recent addition, there were model 3s with back door manual releases back in 2019.
"The new owner's manual for the Europe-bound Model 3 shows that the rear doors are now fitted with an easily accessible manual door release. This is placed at the bottom of the door pocket, under a plastic cover that can be easily removed to access the mechanical release cable. "