With the Economist you can at least do it via email, or if you’re doing digital only you can use a subscription via Apple’s in app purchases etc and manage it that way.
And I had to call to Croatia to cancel mine. There are definitely dark patterns these guys using. Which was very surprising to see from true-journalism-northern-star
I usually “unsubscribe” from these kind of services by changing my credit card to an empty prepaid one and let the payment bounce.