As to if it is time to upgrade grade it depends on your reasons. It will run iOS 18 (the current version) it is going to run iOS 19 it will very probably run iOS 20, so all current applications will be running OK. It will almost certainly run the most restrictive applications like banking apps for the next few years.
It is likely to become outdated at the same time as your wife’s Oppo Reno 11 as Apple phones are typically supported for twice the time android phones are.
So if the amount of memory is not a problem, if the phone is not damaged, if it is not running too slowly, it’s good for years yet, if the battery isn’t holding enough of a a charge it is worth getting a genuine apple replacement battery (the apple batteries are good quality and value for money)