I was a long time Android user - but I realised I was getting through 2 or more phones in the time my wife had one. They'd either become obsolete or just die. I reluctantly bought an iPhone on this basis - it's actually going to work out cheaper if I get 5 or 6 years out of it.
However, I find the iPhone keyboard so bad and the settings concept so muddled that I'm going to return to Android when this experiment is over. Probably not for another 4 years though!
You know you can sell and replace your phone if you don't like it. Recent Pixels have 7 years of support and they don't die. That's what I'd recommend you get instead. You can even trade in your iPhone for up to $700 when you buy a Pixel. You really don't need to force yourself to use a phone you don't like, leave alone for that long.
If we're talking anecdotes, my wife changes her iPhone every 4 years because it gets worse and worse. Daughter does the same. I change my Galaxy every 4 years because it gets worse and worse as well. Not sure how some people can say their <insert beloved brand> holds forever, unless they don't really use it of course. No brand really keeps up with the requirements, unless all you do is make phone calls - which is why my dad still has a Sony Ericsson.