6 hours or more _per day_ sounds absolutely insane though, you must be overestimating that unless you use your phone as a GPS to commute or some similar use case that requires it on in the background.
Interesting. I do use my phone a lot: slack/email regularly throughout the day, twitter addiction, videos in the background while doing other stuff, and reading; but you might be right that I'm overestimating it. (Screen Time says about 7 hours, I have no idea what that counts though)
Regardless, if the consensus in reviews is about 5 hours asking for 4 isn't crazy, especially since (IIRC) iPhones tend to do better than Android in battery life.