using( var workbook = Workbook.Load( "test.xlsx" ) )

  {
    // Get the first worksheet. A workbook contains at least 1 worksheet.
    var worksheet = workbook.Worksheets[ 0 ];
        
    // AutoFit the rows "I" to "P", from 6th and going right, and make sure the row's heights are between 0 and 409.

    worksheet.Rows[ "I","P" ].AutoFit( 0, 255, 5);

    // Save workbook to disk.
    workbook.Save();
  }