How to change section break in ASP.NET Core Word document?

using Syncfusion.DocIO;
using Syncfusion.DocIO.DLS;

using (FileStream fileStreamPath = new FileStream(Path.GetFullPath(@"../../../Input.docx"), FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
{
    //Open an existing Word document.
    using (WordDocument document = new WordDocument(fileStreamPath, FormatType.Docx))
    {
        //Replace the section break with page break in the Word document.
        ReplaceSectionBreakWithPageBreak(document);
        //Create file stream.
        using (FileStream outputFileStream = new FileStream(Path.GetFullPath("../../../Sample.docx"), FileMode.Create, FileAccess.ReadWrite))
        {
            //Save the Word document to file stream.
            document.Save(outputFileStream, FormatType.Docx); 
        }
    }
}

/// <summary>
/// Replace the section break with page break in the Word document.
/// </summary>
private static void ReplaceSectionBreakWithPageBreak(WordDocument document)
{
    //Add page break and removes section break by moving the section items to the first section.
    while (document.Sections.Count > 1)
    {
        WSection sec = document.Sections[1];
        //Add page break in last paragraph of the section.
         (document.Sections[0].Body.AddParagraph()).AppendBreak(BreakType.PageBreak);
        //Iterate the section items in the Word document.
        foreach (Entity entity in sec.Body.ChildEntities)
        {
            //Merge the next section to first section before removing it.
            int lastItemIndex = document.Sections[0].Body.ChildEntities.Count;
            document.Sections[0].Body.ChildEntities.Insert(lastItemIndex, entity.Clone());
        }
        //Remove section at the specified index from the Word document.
        document.Sections.RemoveAt(1);
    }
}