Apple ID Balance
How can I remove my Apple ID balance so my debit card can work?
iPhone XS
Either buy something more expensive and pay the balance with a credit card or contact iTunes Support and ask them to zero balance your account. Either use the form or scroll to the bottom of the page in the 2nd link. Follow through the screens to get a chat or telephone option. You may need to pick a problem that is slightly different than yours to get a chat option.