You should create output nodes in your graph, you can do that quickly by right clicking on the "base material" node and selecting Create/ Output nodes (when it asks if you want to create nodes for hidden connectors, select "No").
- Then Right click in the graph and select "View outputs in 3d view".
- Make sure you also use the Tesselation shader in the 3D View: Materials / Default / Definitions / physically_metallic_roughness / Tesselation.
- And finally adjust the displacement intensity in the shader parameters: Materials / Default / Edit : Adjust the "Height Scale" value.