There are a few services you can sign up for without any of those... but Apple has a support page telling you how to unsubscribe from those from the devices you

There are a few services you can sign up for without any of those... but Apple has a support page telling you how to unsubscribe from those from the devices you signed up from: https://support.apple.com/en-us/HT211011 https://support.apple.com/en-us/HT211011 Said support page also says you can contact Apple Support about it, which I imagine would also work for the "canceling an arbitrary in-app subscription" issue.