If all you did was connect via BT, you should be fine. If you allowed the car to download. / sync anything from your phone like contacts, that info would be retained in the car.
I didn’t delete my phone from the dealer’s car. My contacts were loaded into the car. The sales rep did this and I didn’t know any better to stop him from doing this. This is now two days later. Do need to do anything? The car was sold today.