I wanted a Tesla, until about seven or eight years ago when they switched off features after some dude bought his Tesla used, because only the original owner had paid for the features.
I knew this is what it would turn into. Fuck Tesla, and fuck Musk.
Here ya go: https://www.jalopnik.com/tesla-remotely-removes-autopilot-features-from-customer-1841472617/
Edit: Ah, sold privately, as in directly between individuals? I'm not sure about that, but they totally could. They can track the location of the car; if it starts getting parked at a different house regularly, for example, it'd be easy to tell it'd been sold.