The idea is to have easy jump and quick fall. E.g. by lowering the gravity during jump and doubling the gravity during fall (which detected by `velocity.y < 0`).

kinematicbody_jump.gd

# No warranty to immediately work. May need additional configuration

export(float) var jump_height : float = 64.0

var world_gravity : Vector3 = Vector3.DOWN * 10.0
var move_velocity : Vector3 = Vector3.ZERO

# Handle player jump movement implenented with KinematicBody
func action_input_jump(delta : float) -> void:
  world_gravity = Vector3.DOWN * 10
	move_velocity += world_gravity * delta
	
  # Read input action name "cl_move_up"
	if Input.is_action_just_pressed("cl_move_up"):
		if self.is_on_floor():
			move_velocity.y = jump_height
	
	if !self.is_on_floor() and move_velocity.y < 0:
		world_gravity = Vector3.DOWN * 256
		
	move_velocity = move_and_slide(move_velocity, Vector3.UP, true, 4)