Getting xbox live gold or game pass subscription without converting it after entering the...

Hello! Due to my impossibility to send a request online to the support because of the stupid virus corona, before buying a new subscription is it possible when buying online less expansive for a gold xbox live for 1 month to use only the multiplayer gold
instead of having the ultimate?

I would buy a gold ordinary subscription online and use only for online without the system converting it in ultimate.

I guess the system in order to continue after entering the code it automatically converts the subscription.

Thank you!

:)