Battery degradation is a pretty minor issue and not one I would consider sufficient to justify a new phone, if everything else with your current phone is working well and meets your needs.
My two-year old Xs Max has battery at 84% and I'm having it replaced at the Apple Store - $69.00. (If you don't have a store nearby, there are lots of other places that can do the same thing).
I'm keeping my own Xs Max for as long as it is working satisfactorily. It has just a couple of payments left (AT&T) and I'll welcome the lower monthly payments for my cell plan.
I get the attractiveness of a new phone, but for myself I don't do that much with the camera, so the latest and greatest camera is not going to be a huge deal for me. Likewise my phone has more than enough storage space (256 GB which was more than it turns out I need, by a lot) so I'm not running out of storage.
The phone will loose value in another year and different folks will have different perspectives on the cost-benefit of getting a new phone every 2 years, or even more frequently. There is another thread on the forum here where someone is making the argument that they are better off selling their phone and buying a new one each year.
I'm not sure that I notice any difference in battery life with my own phone at 84%, do you (at 87%)? Apple considers anything above 80% to be fine.
Different strokes for different folks!