How would I go about making flying mechanics for a dragon?

The best example I found was this video for what I’m looking to (hopefully) achieve. I’ve gotten as far as pressing a button to enable/disable flight, and actually moving in-flight along the X and Y axis. But that’s about it… Doesn’t help that there’s practically no tutorials around to help with it. To be fair, it IS pretty specific.
Any help is appreciated! :3