Hey first of all welcome to the forum !
i use iphone since iphone 4, while having never problems with the battery.
I used changed from the Iphone 6S Plus to a 7 Plus.
On the 6s+ after 5 months of use i had about 1,5 days of Batery with about avaged use of the phone ( with intensive use about 15 hours )
With the Iphone 7 Plus i got about 2 days with my battery.
If i compare it with the android phones is tested/ had in the past its not worse on battery life.
Hope is helps u out