"Pilot and Co-Pilot of a plane"
If I may indulge in a minor pedantic moment.
That terminology is not entirely correct.
At any one point in time, there is one and only one PIC (Pilot-In-Command, or "Captain" in old-school terminology). They are the person where the buck stops. They are the person in which the law vests ultimate authority over the operation of the flight.
For the majority of operations its PF/PNF (Pilot Flying / Pilot Not Flying). Whereby PF is responsible for "Aviate" and PNF is responsible for (Navigate, Communicate etc). The role switches round in flight as necessary.
So for the most part (and in order to foster good multi crew cooperation), the two people at the pointy end are considered equals (hence PF/PNF instead of pilot and co-pilot).
The seniority aspect of the Pilot-In-Command only comes into play in limited circumstances. For example, where exercising of their legal authority is required, or where a "Captain's only" flight task is required (e.g. landings at certain tricky airfields or certain weather conditions are deemed "Captain's only" by many airlines).
Finally, I would urge you not to compare a Tesla so-called "autopilot" to the more complex environment of a large commercial aircraft, of which the actual "autopilot" bit is just the tip of the iceberg. Lots of safety and redundancy measures built in at every step that you will never find in a Tesla.