https://photos.app.goo.gl/fk5s31CBWf7FpH6h9
Not really sure what the issue is here, it seems you are talking about “tiling”. When you are adding these textures to your terrain, for you to get detail up close they need to be tiled over and over, when something is tiled over and over its easy to spot the repetition, this even applies to the real world if you look closely at patterns on things like laminate flooring, its the same pattern repeated.
If this is your issue, to fix this, you will need perfect tiling textures (which is near impossible), or look into custom shaders for your terrain (either buy one or make your own). This old article outlines some common techniques which are still relevant to any game engine.
https://docs.unrealengine.com/udk/Three/TerrainAdvancedTextures.html