Nimble is a simple that adds smooth transition animation on player perspective changes. It also make screen rolls when you fly by using elytra, and switch perspective when you riding a vehicle.
The third-person front view is now requires holding F4.
Client-side only. All these features can be disabled or configured if you have installed Kiwi (Fabric). Besides, in-game config UI is provided if you have installed Cloth Config (Fabric)
Elytra: https://imgur.com/a/DufQUv2
Thanks to quat1024's Auto Third Person for the inspiration