public void SetName( 
   string name
)

//Change the name of a layout.

//Perform on the worker thread
await QueuedTask.Run(() =>
{
  layout.SetName("New Name");
});

//This example creates a new layout using a minimum set of parameters.

//Added references
using ArcGIS.Desktop.Layouts;                    
using ArcGIS.Desktop.Framework.Threading.Tasks; 
using ArcGIS.Desktop.Core;

public class CreateLayoutEx1
{
  async public static Task<Layout> CreateBasicLayout(double width, double height, LinearUnit units, string LayoutName)
  {
    Layout layout = null;
    await QueuedTask.Run(() =>
    {
      layout = LayoutFactory.Instance.CreateLayout(width, height, units);
      layout.SetName(LayoutName);
    });

    //Open the layout in a pane on the UI!
    await ProApp.Panes.CreateLayoutPaneAsync(layout);

    return layout;
  }
}

//Create a new, basic layout and open it.

//Create layout with minimum set of parameters on the worker thread
Layout lyt = await QueuedTask.Run(() =>
{
  var newLayout = LayoutFactory.Instance.CreateLayout(8.5, 11, LinearUnit.Inches);
  newLayout.SetName("New 8.5x11 Layout");
  return newLayout;
});
      
//Open new layout on the GUI thread
await ProApp.Panes.CreateLayoutPaneAsync(lyt);