Yes, multiple domains is supported where you can set the primary domain (the domain used to during registration), the secondary domain (the other domains that you have) and domain alias (ie domain name, used as an alias for other domains).
Managing multiple domains:
https://support.google.com/a/topic/29164
How to setup multiple domains:
https://support.google.com/a/answer/7502379?hl=en&ref_topic=3542755