Oauth user log in privilege

Hi previously I have done the Authorization for Oauth user by jmes path it’s working fine now.
role_attribute_path = contains (group[*], “admin”)& “Admin” || “Viewer”
Here if person belongs to admin group he can get admin permission other wise Viewer permission.
Now My question if the Oauth user is not in a group like on above example admin group then I would like to make that he is not able to log in to the grafana isn’t this possible?

That is not possible - https://github.com/grafana/grafana/issues/23218

Isn’t possible for LDAP or any other authentication process?