Other than your carrier give it for free or cheap, I don’t really see the reason why should you buy new phone. I’ve been using Redmi Note 9 for past 3 years and recently got my had on Poco F5. I don’t see the point of my ‘upgrade’. I sold it and come back to my Note 9. Gaming? Most of them are p2w or microtransaction garbage or just gimped version of its PC/Console counterpart. I mean, $400 still get you PS4, TV and Switch if you don’t mind buying used. At least here where I live. Storage? Dude, newer phone wont even let you have SD Card. Features? Well, all I see is newer phones take more features than it adds. Headphone jack, more ads, and repairability are to name a few. Battery? Just replace them. However, my Note 9 still get through day with one 80% charge in the dawn. Which takes 1 hour.
I am genuinely curious why newer phone always selling like hot cakes. Since there’s virtually no difference between 4gb of RAM and 12gb of RAM, or 12mp camera and 100mp camera on phone.
I used to get a new one every two years. Back then the changes were big enough to make it worthwhile. Nowadays there is not much to get from a new phone other than the hardware keeping up with the software and an improved camera.
I’d say, as with any device, keep it until it annoys you or doesn’t get any more security updates.
My iPhone 11 from 2019 starts to feel laggy and the touch screen is not responding as well anymore. Battery health is still over 90% but due to higher energy demand of the newer OSs and apps I often still need to juice up during the day. So this year I’m finally going to get the new model but I’ll keep the 11 as a webcam.