From quick googling, it does sound like OpenID Connect plugin has a manual user sync job you can run. See https://docs.moodle.org/30/en/Office365#User_sync.
But the docs link is broken so, I guess ask the plugin creators? https://moodle.org/plugins/auth_oidc
They do seem to be active and resolving issues with this functionality: https://github.com/Microsoft/o365-moodle/issues/239