[MSCE / ORD C#] Question around getting geometry for elements obtained via GetGraphicElements

Hi, Usually I get entities like alignments, corridors and terrains by accessing geometric model of an active DGN model:

var activeConnection = new ConsensusConnection(Session.Instance.GetActiveDgnModelRef());

var activeGeometricModel = activeConnection.GetActiveGeometricModel();

// access activeGeometricModel.Alignments & process alignments

But not all elements are not in a geometric model. For e.g., elements like BRep Cells or extrusion solids. But I can see them via GetGraphicElements() method of DgnModel.

I attached a DGN file. How can I get geometry data like surface area or volume of various elements? Which C# .NET API can help here?

3566.CBR71018_3D Model.dgn