This is essentially an updated version of PA Headlamp Ray Remover by brianray1, with the main difference being that only the beam/light cone is removed, whereas in the original, the light effect/circle on the headlamp itself was also removed, which I disliked. I do however, like the fact that the original mod made headlamps usable in 3rd-person, where before the effect was so opaque that it was ironically difficult to see through. No assets from the original mod are used, I had to manually edit every headlamp to do this, but I believe the end result is worth it.

As of the time of posting this, this is up-to-date as of the Atlantic City/Season 15 update, but be sure to check the changelog to see if it's updated for future versions.

To install, first create a "Fallout76Custom.ini" in the following directory (if you don't already have one):
C:\Users\Username\Documents\My Games\Fallout 76\

Then, put the following lines in the Fallout76Custom.ini:
[Archive]
sResourceArchive2List = NoHeadlampBeam_M.ba2,

or, if you have multiple mods:
[Archive]
sResourceArchive2List = ExampleMod1.ba2, ExampleMod2.ba2, NoHeadlampBeam_M.ba2,

then, simply place "NoHeadlampBeam_M.ba2" in your Fallout 76 data directory, which by default is:
C:\Steam\steamapps\common\Fallout76\Data\

Optionally, repeat the steps above but with "NoHeadlampBeam_T.ba2" if you want the optional addon that makes all headlamps very bright.

Enjoy!