From this support article --> How apps, content, and subscriptions from Apple are billed - Apple Support
Some purchases aren’t charged to your Apple Account balance
● You can't use your Apple Account balance to send gifts or gift cards.
● For some recurring charges, like AppleCare+, you can't start your subscription with Apple Account balance. But as long as you keep another valid payment method on file and your Apple Account balance would cover an entire charge, your recurring charge will pull from your Apple Account balance (see the article for more information).
● Some subscriptions might not be charged to your Apple Account balance.
● If you use Family Sharing, your family members can't spend your Apple Account balance. Funds that you add to your Apple Account balance are available only to you.