I just set a reminder for +1 year minus 2 days in my calendar and live happily knowing I'll be notified when the time is right.
I wonder when they'll turn Siri to an agent trying to upsell/keep you. Fast forward to the above date:
"This is your reminder to cancel Apple TV plus. But you'll be missing Season 2 of The Morning Show, airing in 4 days. I can offer you a subscription for half price, do we have a deal?"