In this tutorial we’re going to build a simple squash-and-stretch rig in Unreal Engine 5. The goal is straightforward: we’ll take a sphere, give it a single bone, create two controls, and use a little bit of math to make the sphere stretch when the controls move apart and squash when they move together.
https://dev.epicgames.com/community/learning/tutorials/1drB/unreal-engine-fortnite-you-only-need-one-bone-for-this-ue5-animation-rig-tutorial