Is there a way I can transfer my apple account balance to my Apple Card account

No, that is not possible, see -> Check your Apple Account balance -> Check your Apple Account balance – Apple Support (UK)

scroll to ⤵️

If you have an Apple Account balance that you can’t use

You can't redeem or return Apple Gift Cards, App Store & iTunes Gift Cards or unused Apple ID balance for cash, except as required by law. If your jurisdiction allows the refund of redeemed gift balances, you can contact Apple Support to request a refund. 

When you contact Apple, include the following information:

•           Your Apple ID.

•           The refund amount.

•           Your current delivery address.