I toyed with this a few years ago. Here’s a quick UE4 mockup:
You can use a noise sample ofc but I’ve found they are quite expensive for pixel use, and not very artistically controllable.
Instead I just use a cube map to drive the noise. The image here just shows UE4’s default cube map texture which adds a nice little bit of detailing/textural detail over standard noise. You could go all in and bake out a cubemap with what you want, though.
In this particular case I couldnt find a way to pull decal size in the shader, but thats not really the focus on this.
I’d personally stick down this route, its content driven by the cube artwork and is a single tex sample. I personally wouldn’t use decals for UE4 but needs must. You could prob pretty easily make it look like it’s burning by being clever with your cube map info and running through gradients too.