Is it possible to increase triangles on a mesh?

My Displacement maps wont work because of the lack of triangles. Is there a way I can increase the wireframe counts? I am really stuck on this and cannot seem to find the answer.

The two pictures with the pebbles are just a good example, the sphere has lots of geometry and looks good, but the plane does not have as much geometry and just looks wavy. The wall with the bricks is what my project currently looks like. I need it to look like it does in the bricks26 cube. I have also attached a picture of my displacement map material editor.

Any input on this would be greatly appreciated!

Not in unreal, you need to use a 3d application like Blender, 3DS Max or maya. But you can decrease a mehs whit LOD in Unreal engine 4. You need to set the LOD value yourself . I Hope it helps

You can do in modeling mode In mesh category with remesh.