Post Process Materials documention - can't find Random in material editor

Hello!

I’m fairly new to Unreal but not to game development.
I was following this official documentation page:

And in the CustomDepth Stencil section, the writer shows a ‘Random’ node, that takes an index and outputs, I assume, a randomized number. The writer doesn’t mention any ulterior blueprinting or logic to be dealt with, but I can’t find any ‘Random’ component in the material editor, would anyone know what is up with that?