Yes.Selling my wife's 2016XC60. Is it possible to transfer one's VOC subscription to the new owner of your vehicle?
The explanation should be in the Sensus with VOC manual. Here is a sample for MY16 XC90.
The key points that I saw / heard were:
1. Contact Volvo to cancel your service.
2. Current owner should remove the car from the App and possibly reset your car to factory settings - but see what Volvo Care instructs you to do.
3. The remaining subscription follows the VIN.
4. The new owner would contact the dealer to initiate VOC and retrieve credits if any.
Never done it so this is novice, arm-chair advice. Good luck.