What would happen if I add an index to a record type into production that wasn't there before in CloudKit?

I found the following here: Designing and Creating a CloudKit Database.

Important

During development, you can change your schema as much as you want, but once it’s deployed to production, you can’t delete any part of it. You can only make additive changes, such as adding a new field to a record type, or adding new record types.

This still doesn't tell me if I can add or remove indices to record types after production. I would need less to remove indices than to add indices.

Again I find this: The Development and Production Environments

After you deploy the schema to the production environment, you can still modify the schema in the development environment but can’t delete record types and fields that were previously deployed.

This still doesn't specifically tell me exactly what I want to know.