For endpoint-based mapping, try inserting a record into the sa_pattern_map_run table via the Table API — include the target endpoint and related service in the body and it should trigger the mapping run.
For tag-based, it depends a bit on your instance version, but look at the sa_tag_based_service table as a starting point. Also worth checking the REST API Explorer on your instance and filtering for Service Mapping — you might find something out of the box that fits your exact use case.
Let me know if that works!
