Apple is the only company in the world to still support a 5-years old phone and push major updates that still bring new features. They will pull the plug after 6 whole years.I still have one (to bring on vacations) and it still works fantastically well. Considering iOS 14 is its final version, it will ALWAYS work well.
I even have an iPhone 5 that works well, slightly slow sometimes, but it's definitely useable. Starting from iPhone 5S, planned obsolescence is no more.