How to get new materials

Hello forum !

I stumbled on a material that I want, please check:

And I found where the files are:

I tried overwritting the 3 lighting files in the core file but I get the error: UseReflection is undefined

Where can I download latest materials package please?

I probably don’t understand your problem.
Why would you modify your core ?
Can’t you just put that in your own assets/packages ?