The iPhone 12’s battery life is claimed to be 17 hours of video playback, the same for the iPhone 11. The 12 Mini is supposed to be good for 15 hours under the same circumstances compared to the new SE at just 13 hours. I have no trouble getting a day’s use out of my SE’s battery.
Go to https://www.apple.com/iphone/compare/ & click on “See all models."