And they just release iOS 16.7.8 last month, that was the 4th update this year for iOS 16, that goes back until the iPhone 8 from 2017.

They also released iOS 15.8.2 this last march, this one goes back to the iPhone 6 from 2015, a device that is 9 year old and still getting security updates.

So while they are only making a commitment for 5 years, in practice they are doing, and have usually done, for much longer then that.