I would like to suggest 2 possible items.

The first is a section of track travelling under a diagonal bridge section. Possibly one with a track going over the bridge, as well as track going under it, and a section of track going under a road bridge.

The second idea is for a section of track traversing a mountain. At present, I have only been able to create layouts with tracks going through a mountain, which I belief is the only built-in option.

Hope these ideas are helpful.