I've seen a lot of complaints regarding battery life in iOS 12 compared to 11 and 10. I upgraded my iPad Air 2 to iOS 12, and while the OS feels (just) a little bit snappier, battery life has been considerably worse than 11.4.1 (clean install), the iPad has only 16 battery cycles, so it's no where near consumed (battery health at 99% according to coconut battery app)
Well, the good news is that Apple is still signing iOS 11.4.1, that means you can downgrade to iOS 11 from 12. the bad news is that they'll stop signing 11.4.1 soon, so if you regret upgrading to iOS 12, downgrade now while you still can.
Downgrading tutorial: https://www.macworld.co.uk/how-to/apple/downgrade-ios-12-3664217/
I downgraded my iPad to iOS 11 and surprisingly, the battery life is back to normal.
Well, the good news is that Apple is still signing iOS 11.4.1, that means you can downgrade to iOS 11 from 12. the bad news is that they'll stop signing 11.4.1 soon, so if you regret upgrading to iOS 12, downgrade now while you still can.
Downgrading tutorial: https://www.macworld.co.uk/how-to/apple/downgrade-ios-12-3664217/
I downgraded my iPad to iOS 11 and surprisingly, the battery life is back to normal.