Earlier quoted context omitted.
My iPhone 12 mini is a bit over 1.5yrs old and has a 86% battery health. I hope this trend does not continue as fast or I guess I'll have to replace it sooner than later.
That sounds pretty fast, my 12 Pro Max is roughly the same age and at 96%
Mine is an iPhone 7 I bought refurbished back in February 2017. This phone is likely to have seen less use than a friend of mine's phone bought at the end of 2021. It spends 95% of its life connected to a power source (even when I actively use it), so I expect the battery to last quite some time.