How long after, when you first install Windows 10 it can take 24 hours to settle down, it is trying to Sync data from many sources and this is what leads it to run hot and use up battery.
Whenever I do an upgrade, I always get the process finish, making sure all apps are up to date as well, then I do an normal restart and leave the phone off for a few minutes, then hopefully it is ready to go.
Apart from checking for app updates go into settings and battery and battery usage by apps and see what is using up your battery, I find Edge to be one of the worst culprits so I click on it and set it to never allowed in background.