Documentation for adding scopes missing from the main docs?

I wasn't seeing anything about adding scopes at the main doc page: https://developers.google.com/identity/sign-in/ios/quick-migration-guide.

Also, in the main docs, the section:

"Retrieving user information
Once the user has authenticated and authorized access to the scopes you request, you can access user profile information through the GIDGoogleUser object."

(https://developers.google.com/identity/sign-in/ios/people) it makes it sound like you can explicitly request scopes prior to the `addScopes` call.