I know how to flip text on AE, but I'd like to animate the flip and I couldn't find a tutorial for that.
I have a 9 and I want to copy it and flip it like opening a book like this:
I found the answer to my own question... I have to go to the text layer I want to animate, click on animate, select enable per-character 3D and then change Y Rotation to -180 degrees.
This tutorial helped http://www.premiumbeat.com/blog/creating-3d-flip-down-text-in-after-effects/