Neither the purchase or the subscription is managed by Apple.
As with any credit card purchase, you must contact the merchant who you paid for how you would cancel a subscription you made with them. If you are not able to resolve the problem with the merchant, then you have to dispute the charge with the bank of the issued card.
Just because you used Apple Pay does not mean Apple is involved in the transaction. The use of Apple Pay means the merchant does not have your actual credit card number of the card you chose to make the payment with. When you added the card to your Wallet, the bank gave you a unique token that is stored on your device to use for purchases. When you use the card in the Wallet, it requires you to double click the side button to approve the charge, followed by Authentication with Face ID/Touch ID or Passcode. Once that is done, the unique token your bank gave you is sent to the merchant, without them knowing your credit card number.
Fraudulent charges are still resolved the same way they do with any other credit card transaction. In this case, you likely inadvertently signed up for a free trial that would have probably been in the fine print of the initial results you paid for. When you dispute the charge with your bank, the first step they will have you do is attempt to contact the merchant for a resolution. If the is unsuccessful, then they will proceed to block further transactions, issue you a new card, and possibly refund your money. None of this involves Apple.
Also, be aware this is a common scam spread on Social Media where the posters receive money for directing users to their website, and also you see this as advertisements on there as well. Consider that risky behavior and don't believe everything you read on Social Media.
