使用Open Xml SDK 2.0更改Wor Document的页面大小

using System.IO;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Wordprocessing;

namespace ChangePageSize
{
    class Program
    {
        static void Main(string[] args)
        {
            using (WordprocessingDocument document = WordprocessingDocument.Open("input.docx", true))
            {
                // Find the section properties in the document
                SectionProperties sectionProperties = document.MainDocumentPart.Document.Body.Descendants<SectionProperties>().FirstOrDefault();

                // If the section properties exist, update the page size
                if (sectionProperties != null)
                {
                    // Update the page size
                    sectionProperties.PageSize.Width = 12240; // 12240 Twips = 11 Inches
                    sectionProperties.PageSize.Height = 15840; // 15840 Twips = 8.5 Inches

                    // Save the changes to the document
                    document.Save();
                }
            }
        }
    }
}