Can I lock my Apple Card or Account to stop automatic payments?

The physical Titanium card can be locked just like other bank cards, but the virtual card cannot.

Lock or unlock Apple Card - Apple Support

If you are seeing payments charged to your card regularly, then you have a subscription that you need to cancel with that merchant. A subscription is a legal obligation to pay for those charges. You will find that locking a card does not cancel a subscription. To cancel a subscription, first you are required to contact the merchant, and if unsuccessful in cancelling the subscription, it can be disputed as fraudulent with the bank of the issued card. That would be Goldman Sachs for the Apple Card.

You can lock a Physical Titanium Apple Card. click here ➜ Lock or unlock Apple Card - Apple Support

You cannot lock your Apple Card account or prevent recurring subscriptions from being charged. If you no longer want to have a subscription with a specific Merchant to be charged to your Apple Card, then you need to go cancel it with the specific merchant.

Ducking payments constitutes fraud. You are liable for the blocked amounts and the merchant can sue for due payments.

Locking a card is not a way to prevent subscription charges. Here is an example of that feature offered by Capital One that makes it clear. I think you may have just misunderstood the use of the Card Lock feature, as it is useful if your card is lost or stolen to prevent new charges.

Locking a credit card prevents the card from being used to make most new purchases. But your credit card company will likely continue to authorize any recurring charges you already approved, like subscription payments or automatic bill pay.

https://www.capitalone.com/learn-grow/money-management/card-lock/