How to force all GSuite users to change password.

At the root level select the option to add multiple users from CSV file.

Also check in the option to populate with users, save the file.

All you need to do is import the same file with the option to "Require User to change Password at next sign-in" checked in.

This can be really useful when deploying Google Cloud Password Sync because  passwords are only updated on a AD password change event which can be a problem when you first install. 

School's aren't keen on getting everybody to change their passwords in the middle of the year so you can seed all the accounts with a fixed password or some known hash of the student ID and then run the import to force them to update with their AD passwords. 

From this point the sync takes over and keeps it all in line. Of course this only works if the AD password is 8 chars or more.