Data Protection Addendum and Standard contractual clauses

Hi Everyone, I have the below queries when it comes to signing of DPA and SCCs 1. In which scenarios do we sign a Data protection addendum(DPA) and standard contractual clauses(SCC) with the vendor? For e.g. there is a scenario where we will be sharing our European customer PII data with the vendor and the vendor will be storing that data in a non-EU region. In this case, we sign DPA and SCC with the vendor. What are the other scenarios where we sign DPA and SCCs with vendors?