A purchased subscription made without my knowledge
How do I get a refund for a subscription I was unaware of
iPhone XS
First you need to cancel the subscription, no matter who signed up for it.
View, change, or cancel your subscriptions - Apple Support
Then you need to speak to whoever purchased the subscription without your knowledge. Frankly, I don’t know how that’s possible unless that person knows your Apple ID and password.
Then you need to contact Apple to see if they will grant a refund.