Apple Music individual vs family plan
Can everyone with same Apple ID be on individual plan
Question marked as
An individual plan is for a single Apple account. So, any device or computer signed into the same Apple account has access to the Apple Music plan for that individual, subject to the normal limits (10 devices with a maximum of 5 of those being computers).
However, if you are indicating that multiple people are using the same Apple account, that is a very bad idea that will result in other things getting shared like messages and phone call logs, and all purchases will be charged to the payment method on the Apple account.
Best,
GB