I can't find subscriptions on my Iphone

Why not? What happens when you follow the steps in the support document you posted from?

If you see no subscriptions listed when following those steps, then that means the Apple ID you are currently using has no associated subscriptions.

If you are being charged for something, and its not listed there, then check if you are the Family Organizer in a Family Sharing group or you share your payment method with someone else. In either case, the subscription would be tied to their account not yours and would need to be canceled from one of their devices.