Kind of, but more than just different primitives, having the ability to make my own geometry that hugs the underlying geo I want to apply the decals to, and then assign the special deferred decal materials to that new custom piece. These shots from the Crytek documentation illustrate exactly the kind of things I’d like to do - note that these are older versions of their decal system that just use opaque materials and alphas, but newer versions of their engine allows full deferred decal materials to be applied to that kind of custom geo:
