@sakuraime Thanks for reaching out.
A subscription can have multiple resource groups, so any permission given at resource group individually is applicable for that resource.
If you give any permission at the subscription, that user can have access to perform some actions at all the resource groups within that subscription.
So bottomline, if you assign a user as a contributor at a resource group level, he will be able to perform those actions at that resource group level with no other permission required to be given at Subscription level.
-----------------------------------------------------------------------------------------------------------------
If the suggested response helped you resolve your issue, please do not forget to accept the response as Answer and "Up-Vote" for the answer that helped you for benefit of the community.