i just built a system that triggers health bar of an enemy to be visible if you are looking at it. You could do something similar.
Make a line trace at whatever distance you need, then if it hits an actor that you can inspect, use a blueprint interface that will handle the trigger. Put a branch that will stop if it’s the same actor if you need. Maybe add a timer or delay node to prevent rapid repeated inspection.
line trace By Channel https://www.youtube.com/watch?v=yo9VrxFgUJY
Blueprint Interface https://www.youtube.com/watch?v=G_hLUkm7v44
I can post a pic of my BP later if you want, I don’t have access to my project at the moment.