If you only know the tag number and get VIN can find out if a car is on repo list?

No, you cannot definitively determine if a car is on a repossession list solely from the tag number and VIN. While the VIN is a crucial identifier linked to vehicle history, including repossessions, access to those repossession databases is typically restricted. Only authorized parties, such as lenders, repossession agencies, and law enforcement, generally have access to such databases. A standard VIN check through a public service will not reveal repossession information.