Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hello Sam Curren,
Good day! Thank you for posting to Microsoft Community. We will be happy to assist you.
Yes, you can manage multiple domains under a single office 365 subscription. However, if you need license for new users associate with the new domain, you need to purchase license/subscription. As per your user requirement, you have to purchase subscription for your new domain.
If I misunderstand you or have any other query, please feel free to let me know. I will continue to assist you. Your understanding and co-operation are highly appreciated.
Thanks for your precious time. Have a nice day!
Sincerely,
Nafis Iqbal Shuvo