This data pack gives the player extra maneuverability by pressing sneak in the air
This was taken from my Ninjas Datapack (Modified Slightly):
https://www.curseforge.com/minecraft/customization/ninjas-new-agility-and-item
Once Installed:
Simply press sneak to spawn an invisible block under your feet for you to jump off of (works only when the jump cooldown has expired and you have touched the ground and reset your double jump),
you can change the jump cooldown in the _load function
(Designed mostly for complex parkour maps)