Mesh Distance Fields can only be improved so much before increasing the DF Resolution Scale has no effect. The DF resolution scale really only continues to work depending on the size of the mesh and complexity of the mesh.
To visualize the difference and troubleshoot Distance Field Meshes you will need to use the viewmode for it by going to the Viewpor > Show > Visualize > Mesh Distance Fields. The DF resolution scale really only continues to work depending on the size of the mesh and complexity of the mesh.
This page’s Troubleshooting and Quality section can help better show off what I’ve described above.