You can do this through the use of Level of Details, or LODs. In UE4, you can place a mesh in your level that switches to a less complex mesh as the player moves away from it in order to make your level perform better. However, the mesh needs to be detailed when the player is up close to the mesh and can see it clearly. There is no point in having a very complex and detailed mesh if it is only taking up a few pixels on the screen and the player can barely see it. However, you do not need that mesh to be very detailed and complex once the player moves far away from the mesh.
When a player is up close to a Static Mesh you have placed in your level, you want the mesh to look very detailed.
