I got this texture from Substance Source then imported it to painter to modify it then I exported the textures to unreal engine 4.
Test it on a high poly mesh
Displacement works with tessellation of mesh. If you create the plane in 3D software and add tessellation to it, the result will improve.
Note that the more tessellation you apply to mesh the more expensive it becomes to use so you need to find a balance of decent tessellation on the mesh and performance.
You can see these links to the documentation about displacement and tessellation in Unreal and the Reddit link to a discussion about displacement in unreal and understand it in more depth.
World Displacement: https://api.unrealengine.com/INT/Resources/ContentExamples/MaterialNodes/1_11/index.html
Understanding Displacement: https://www.reddit.com/r/unrealengine/comments/8swws7/understanding_displacement/
Expanding on what joshbridger said, if you find that the performance you require doesn’t match the tessellation density that you need for the visual fidelity you want, you can try parallax occlusion mapping instead, which essentially simulates geometric depth with a pixel effect instead of a vertex effect.
Totally forgot about Parallax! Would probably be better to use I guess as it’s somewhat cheaper but I guess it depends on what you intend to have the displacement looking like.