Targeting and Attacking multiple enemies.

Hello! I was wondering if I could get pointed in the right direction as to how to make a targeting system where the player can “Shoot” multiple enemies at the same time and how to make a widget or icon appear depending on how close the enemies are to indicate they are in range to receive damage. I have thought of using line-tracing but as far as I can tell that only uses a single line. Here is a link to the video showcasing this mechanic and an image.