Google Oauth2 built in a version 3.6.x.
Please see: https://docs.moodle.org/36/en/OAuth_2_Google_service
On the link above, it shows IAM and Auth Consent screens ... you might also have to do the 3rd tab ... Domain verification for the moodle server. Also, read the App Verification section of link above.
Might need to create a Google account (not someone's personal Google account) to be used as the system account in the config of Moodle.
'spirit of sharing', Ken