// Enable animation blending for all animations
scene.animationPropertiesOverride = new BABYLON.AnimationPropertiesOverride();
scene.animationPropertiesOverride.enableBlending = true;
scene.animationPropertiesOverride.blendingSpeed = 0.02;
scene.animationPropertiesOverride.loopMode = 1;
Or one may use this solution at container level - Animation Blending
There is a lot of different examples of animation blending here at Forum and in the Docs as well - Advanced Animation Methods | Babylon.js Documentation