So I want to create dirt that looks like the dirt in this video here - Unreal Engine 4 Grass Shader Test - YouTube
I do know how to import the textures and connect the uv maps and stuff but it never looks very good.
It always loses the small details
If someone could help it would be greatly appreciated.
The details are usually achieved inside a material using more than one texture. Basically, you have one texture for big features (for example tiles every 4 meters) and a texture for details. You sample the big features texture using TexCoord but use TexCoord * (small details scale) number for the second one. Then you can either add or multiply those two textures and connect to the BaseColor channel. You can do similar thing to the normal map channel. If this is not enough, you can add even more textures. Look at how UE4 achieves good details on metals using this techniques (or for wood) in content samples.