Brand new iPhone 7 battery drains quickly, is this because it’s new ?

Hi guys ! I just bought a brand new IPhone 7 ( had the X) too many bells and whistles ( and too much glass lol ;) . Anyhow , after setup ect.... it seems like the battery ( doing things I would do every day on my other iPhones ( 6s and a 6s plus ) seem to drain the battery? Is this just because it’s new and there is a “ break in” period ? Apple says no ( and that’s there is nothing wrong with the battery) , which I already knew 😉. I am a VERY light user , probably 3-4 short phone calls a day , some texting and occasionally checking the weather or my calendar. My phone shouldn’t be at 21% at 6 pm . Has anyone else had this issue , and if so , will it resolve itself ? If not , it’s going back !

Thanks much