Hey how would i make this sort of scoping system?

So i have an animation for my fps arms (specifically for a sniper), and i want to create a HUD overlay in a certain part of that animation. I am using a pose for my idle and my sniping animation and im using blend poses by bool in my anim graph. So i need to know how some games do this.

Here’s is an example of
what i mean

in here the widget is created at a specific point in the animation, which is what i am assuming.