For example in Outlast when you hiding in locker you can see locker’s door opening and character’s hand opening door and hiding inside. But locker and character are different objects, how can I sync those animations?
You can drive animations in the animation blueprint to behave in every which way. In the case of a locker door, it would be simple enough to swing the door hinge with a lookat rotation aimed at the hand of the player. Then boolean on/off if the door should move off of an open or closed position to that lookat rotation.