Honestly they’re a pretty stable product (minus, of course, the infamous planned obsolescence via battery incident). My iPhones have worked as intended since my first (4s).
I've been using iPhones since the 3GS, then 4S the SE, and now an iPhone 7.
Every single one of them, out of the box, has had terrible battery life.
The iPhone 7 has a 1960mAh, that's just insufficient. Full. Stop. No matter how you slice it, a 2000mAh batter is never going to get you through a day on an iPhone if you actually use it.
I've recently seen Android 10 phones available with 10,000mAh batteries. That sounds like it might at least get me through till lunch time.