Is it possible to allow user to turn auto renew off or back on inside my app? or does a user have to go to iTunes to manage it?
Manage Subscription In-App
Yes, with iOS 15 you can expose the manage subscriptions sheet from within your app. https://developer.apple.com/documentation/storekit/appstore/3803198-showmanagesubscriptions
iOS 14 and earlier can use a deep link but this this will take the user out of your app and into the Manage Subscriptions page. That deep link is: https://apps.apple.com/account/subscriptions And that is documented on https://developer.apple.com/documentation/storekit/original_api_for_in-app_purchase/subscriptions_and_offers/handling_subscriptions_billing