No need to UV unwrapped the objet and no need to link to external image texture.
Fully Procedural photorealistic and detailed materials for Blender 2.82+. The node group give you only the parameter to get realistic render.
WHAT WILL YOU GET?
.blend file with a full PDF notice on how to use the node group or material on your current work.
The nodes generate a base color output, a roughness output, a specular output and a normal output to simply plug to your shader node.