In Android Nougat, the individual apps and services in use by the OS aren't listed, they're just thrown together under one "category" in the battery drain info screen. So that includes everything being used by the system itself (excluding the screen) and that seems to be pretty typical. A better gauge is to use the phone for a few days and see how the battery life holds up.
I do recommend doing a wipe of the cache partition after a system update, but it's optional. I haven't had any issues that weren't cleared up by a reboot or a cache wipe, and the issues have been very few and very far between.