Well based on what I see on the video, it seems Unreal uses a similar yet more automated and interactive approach, based on boxes intersection ( = booleans).
It take note on your comment and see how long it can take to script it 😀
Cheers,
/Thibaut
EDIT:
DECALMachine basically makes the workflow much faster, among many other things. I’m not certain it uses the exact same technique but the result is also topology based. You can see it as an equivalent to hardops for the boolean workflow.