Yes, it's called "App Nap":

Apple MacBook Pro lasts 135 minutes longer on battery in full screen mode https://news.ycombinator.com/item?id=14947703

Apple MacBook Pro 15: How to get 2 more hours of battery life with this simple trick https://www.notebookcheck.net/Apple-MacBook-Pro-lasts-135-mi...

Why do Macs have a longer battery life when in full screen mode? https://www.quora.com/Why-do-Macs-have-a-longer-battery-life...