How to keep players in air similar to JJK Infinite

Ive been really interested in how JJK infinite keeps player in the air so seamlessly, heres a clip of the air combat for example
A couple ways Ive thought of keeping someone in the air is simple things like Anchoring HumanoidRootPart, or using BodyVelocity, or Linear Velocity, but JJK infinites air system seems so smooth and the player is able to move around easily, along with having smooth knockback, so im ruling out Body Velocity, maybe a whole custom physics system, idk
Anybody have any clue what it could be?