This is an overview of new Animation Authoring features that have been added to Unreal Engine 5.4. These include New (Experimental) Gizmos, Upgraded Anim Details, New Tween Tools, Updates to our Constraint system as well as our new Layered Control Rigs.
https://dev.epicgames.com/community/learning/talks-and-demos/BJGZ/unreal-engine-fortnite-animation-authoring-5-4-features-at-a-glance