Alot. 17 hours and 22 minutes later off the charger, I still do not have this issue. All leads me to believe how you use your phone and what settings are on it. No 2 users are different. No 2 users use their phones the same way.
You're going to have to pinpoint how this is happening. No one else can tell you anything beyond what I have said. You don't really give us a good description.
Numerous factors contribute to this.
Question: My phone battery runs low in 4 hours after full charge. I use iphone 7