This Unreal Engine 5.4 video is about starting to build The Tower Manager, which will be responsible for Tower Placement.
We start by importing a png, and using it to create a two-sided translucent material. Next, we create a Tower Object Channel and Tower Collision Preset. Then we create the Tower Base Blueprint, which includes a Box Collision using the Tower Channel and Preset, as well as a Highlight Mesh using the Material we created. Next, the Tower Manager is created to create a set of Tower Base Blueprints, along with some interaction to toggle their highlight based on mouse hit result.
https://dev.epicgames.com/community/learning/tutorials/EPej/unreal-engine-10-the-tower-manager-tower-placement-setup-let-s-make-a-tower-defense-game