Some animation like aim animation should make the target bone move slowly to a target location by time, not teleport to the location. It can be achieved by setting mix time over animations, but i guess there is no option for setting mix time between an animation and empty animation. (mix from empty animation to some other)
I think this is a quite easy question, But i can't see any proper approach to do this.
it will be great if you share any solution or example page for this.