That is always a tricky 'unanswerable' question
Which apps are you running? Any unusual apps that are being reported by the phone (it monitors apps that consume out-of-the-ordinary amounts of battery a day and displays a 'warning')? How many accounts you have syncing and how many are push VS polling (the latter will drain more)? Are you using the screen for how long? Full on brightness vs auto mode vs low brightness? Battery saver mode enabled? (See why this is 'unanswerable'?
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On mine, with MY apps, Sync active on two e-mail accounts and social media, mid-avg use, auto-brightness enabled, no battery saving modes, the phone will make it through a day with at least 20% left to spare. I'm getting much better battery life with this one than what I was getting with an S8 (not the plus, normal one). But again, that's MY usage.
That being said, 7 hours of use, unless it's super intensive, sounds abnormal. Most people I've heard about are getting stellar battery life.