Maybe time to upgrade to the iPhone 17, although you've probably missed the free carrier credit: I think they allow trade in up to 13.
Discussion
I've stayed on my iPhone12 mini because I like it. I actually hate that at some point Apple will no longer support it and force me to upgrade. At that point I'm considering GrapheneOS - even though the UI/UX leaves a lot to be desired.
No need to change if it works for you and you like it. I'm a photographer and want the new camera features and processing that the new iPhones provide (Apple Log for example).