How to create "enlargeable" mesh on Drag & Drop? (See video and image)

Let’s say we have an Actor with a Static Mesh component attached to it.

Everytime the player clicks on the Actor and drags the mouse, I’d like to create an “enlargeable” arrow, that starts at the clicked Actor, and finishes where the user moves the mouse to.

I know this is kind of confusing to understand, this is why I will reference you to a video on Youtube where this effect is shown (time mark 13:23):

Also I attached an image, in case someone can’t watch the video.

This game was made with Unity, so there is no reason why this effect can’t be achieved with Unreal. The question here is, how? May anyone more experienced than me, point me in the right direction?