public CubicBezierBuilderEx( 
   CubicBezierSegment cubicBezier,
   SpatialReference spatialReference
)

{
  // retrieve the bezier curve's control points

  CubicBezierBuilderEx cbbEx = new CubicBezierBuilderEx(bezierSegment);
  MapPoint startPtEx = cbbEx.StartPoint;
  Coordinate2D ctrlPt1Ex = cbbEx.ControlPoint1;
  Coordinate2D ctrlPt2Ex = cbbEx.ControlPoint2;
  MapPoint endPtEx = cbbEx.EndPoint;

  // or use the QueryCoords method
  cbbEx.QueryCoords(out startPtEx, out ctrlPt1Ex, out ctrlPt2Ex, out endPtEx);
}

{
  //Note: Must be on QueuedTask.Run

  //Build geometry
  Coordinate2D pt1 = new Coordinate2D(3.5, 7.5);
  Coordinate2D pt2 = new Coordinate2D(4.16, 8);
  Coordinate2D pt3 = new Coordinate2D(4.83, 7.1);
  Coordinate2D pt4 = new Coordinate2D(5.5, 7.5);
  var bez = new CubicBezierBuilderEx(pt1, pt2, pt3, pt4);
  var bezSeg = bez.ToSegment();
  Polyline bezPl = PolylineBuilderEx.CreatePolyline(bezSeg, AttributeFlags.AllAttributes);

  //Set symbology, create and add element to layout
  CIMTextSymbol sym = SymbolFactory.Instance.ConstructTextSymbol(
    ColorFactory.Instance.BlackRGB, 24, "Comic Sans MS", "Regular");

  var ge = ElementFactory.Instance.CreateTextGraphicElement(
    layout, TextType.SplinedText, bezPl, sym, "this is the bezier text",
          "New Bezier Text", true, new ElementInfo() { Anchor = Anchor.CenterPoint });
}