ArcGIS Pro 2.7 API Reference Guide
From3DModelFile Method
Example 

ArcGIS.Core.Geometry Namespace > MultipatchBuilderEx Class : From3DModelFile Method
The file system location of the 3D model.
The spatial reference of the output geometry.
Reads a supported 3D model from file.
Syntax
public static Multipatch From3DModelFile( 
   string filePath,
   SpatialReference spatialReference
)
Public Shared Function From3DModelFile( _
   ByVal filePath As String, _
   Optional ByVal spatialReference As SpatialReference _
) As Multipatch

Parameters

filePath
The file system location of the 3D model.
spatialReference
The spatial reference of the output geometry.

Return Value

The model geometry. An empty multipatch will be returned if the model file cannot be read or if the model file contains no geometry.
Exceptions
ExceptionDescription
FilePath is not specified.
If the file does not exist.
If the file exists but isn't a normal readable file or the file extension is not supported.
Remarks

The 3D model files that are supported are .3DS, .DAE, .FLT, .OBJ, .gITF, .GLB).

The default spatial reference of the created multipatch will be WGS84 if one is not provided.

Example
try
{
  var model = ArcGIS.Core.Geometry.MultipatchBuilderEx.From3DModelFile(@"c:\Temp\My3dModelFile.dae");
  bool isEMpty = model.IsEmpty;
}
catch (FileNotFoundException)
{
  // file not found
}
catch (ArgumentException)
{
  // File extension is unsupported or cannot read the file
}
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

MultipatchBuilderEx Class
MultipatchBuilderEx Members