Essentially yes, it’s called the Right to Erasure or the Right to be Forgotten. If the user is in a country that adheres to GDPR and the company controlling the data operates in a country that also uses GDPR, then that right applies.

The only reason Google/Gmail wouldnt delete (or wouldn’t be able to delete) some of your data would be if they had a lawful or legitimate basis for holding onto it.

I can’t think of a reason Google would give for hanging on to your data but that doesn’t mean there isn’t one, but they’d have to notify you of that reason as part of their response to your request.