Update service application database in Sharepoint 2016.

Question

Experts, I have already created and configured sharepoint 2016 service application (search service, managed metadata service, user profile service etc..) but already I have these service application ups and running in sharepoint 2013 environment. So how do I Migrate these database to sharepoint 2016 service application.. I have seen many open forums, they are saying create new SA and configure the upgraded SA DB to it. Since already I have created the SA and configured SA db in SP2016... so how can I update service application database or something better approach???? Your input and help is appreciated. Thanks, Rahul