public static SpatialReference WebMercator {get;}

{
  // create a point with z, m
  MapPoint point = MapPointBuilderEx.CreateMapPoint(
           100, 200, 300, 400, SpatialReferences.WebMercator);

  // set the flags
  WktExportFlags wktExportFlags = WktExportFlags.WktExportDefaults;
  WktImportFlags wktImportFlags = WktImportFlags.WktImportDefaults;

  // export and import
  string wktString = GeometryEngine.Instance.ExportToWKT(wktExportFlags, point);
  MapPoint importPointGeom = GeometryEngine.Instance.ImportFromWKT(
        wktImportFlags, wktString, SpatialReferences.WebMercator) as MapPoint;

  double x = importPointGeom.X;       // x = 100
  double y = importPointGeom.Y;       // y = 200
  bool hasZ = importPointGeom.HasZ;   // hasZ = true
  double z = importPointGeom.Z;       // z = 300
  bool hasM = importPointGeom.HasM;   // hasM = true
  double m = importPointGeom.M;       // m = 400

  // export without z
  WktExportFlags exportFlagsNoZ = WktExportFlags.WktExportStripZs;
  wktString = GeometryEngine.Instance.ExportToWKT(exportFlagsNoZ, point);
  importPointGeom = GeometryEngine.Instance.ImportFromWKT(
    wktImportFlags, wktString, SpatialReferences.WebMercator) as MapPoint;

  x = importPointGeom.X;        // x = 100
  y = importPointGeom.Y;        // y = 200
  hasZ = importPointGeom.HasZ;  // hasZ = false
  z = importPointGeom.Z;        // z = 0
  hasM = importPointGeom.HasM;  // hasM = true
  m = importPointGeom.M;        // m = 400

  // export without m
  WktExportFlags exportFlagsNoM = WktExportFlags.WktExportStripMs;
  wktString = GeometryEngine.Instance.ExportToWKT(exportFlagsNoM, point);
  importPointGeom = GeometryEngine.Instance.ImportFromWKT(
    wktImportFlags, wktString, SpatialReferences.WebMercator) as MapPoint;

  x = importPointGeom.X;        // x = 100
  y = importPointGeom.Y;        // y = 200
  hasZ = importPointGeom.HasZ;  // hasZ = true
  z = importPointGeom.Z;        // z = 300
  hasM = importPointGeom.HasM;  // hasM = false
  m = importPointGeom.M;        // m = Nan

  // export without z, m
  wktString = GeometryEngine.Instance.ExportToWKT(
    exportFlagsNoZ | exportFlagsNoM, point);
  importPointGeom = GeometryEngine.Instance.ImportFromWKT(
    wktImportFlags, wktString, SpatialReferences.WebMercator) as MapPoint;

  x = importPointGeom.X;        // x = 100
  y = importPointGeom.Y;        // y = 200
  hasZ = importPointGeom.HasZ;  // hasZ = false
  z = importPointGeom.Z;        // z = 0
  hasM = importPointGeom.HasM;  // hasM = false
  m = importPointGeom.M;        // m = Nan
}

{
  MapPoint pt = MapPointBuilderEx.CreateMapPoint(1.0, 3.0, SpatialReferences.WGS84);
  Geometry result = GeometryEngine.Instance.Project(pt, SpatialReferences.WebMercator);
  MapPoint projectedPt = result as MapPoint;
}