Hi Bernando! If you set that env var to false, i’m afraid the only way to grant admin rights is by changing the role field in the db. This does not operate at db user roles, but purely at how access control is handled in the server application itself:
Quite a few popular CMSes, like wordpress, ghost, strapi, etc. work like this. If that’s disabled, there’s no server admin - beyond the person in charge of the deployment/whoever has access to the db.