According to the tutorial, Kent has the vertices and faces over the sculpt. But somehow I dont get mine the way as it is in tutorial.
I can turn on "X-Ray"--> Then I see also the back faces from the otherside.
One way to see the Faces, but not the backfaces is to set the Viewport Display in the Object Properties tab to In Front and in the Viewport Shading check Backface Culling:
If you give the retopology a Material, you can then set the Viewport Display Color to something you like, if you want.
And to get the Backface Culling to work properly, you'll have to set the Alpha of the Face Color to 0 in the Preferences > Themes > 3D View:
