The ability to change the natural jump height in Custom Servers. This would be in the form of a toggleable Operator setting.
This refers to the jump height of a player. Generally in Minecraft you can jump 1 block high. This would allow players to jump 2+ blocks high naturally, up to a certain point (10 blocks perhaps?).
Additionally, this could be like ‘gravity’, so anti-gravity - like on the moon. Meaning that you jump and fall slower/fall.