新建控制台程序

添加包Syncfusion.Pdf.Net.Core包，当前官方的版本号为26.1.39

直接上代码

Syncfusion.Pdf.PdfDocument pdfDocument = new Syncfusion.Pdf.PdfDocument();
for (int i = 1; i <= 10; i++)
{
    var page = pdfDocument.Pages.Add();
    PdfGraphics graphics = page.Graphics;
    PdfFont font = new PdfStandardFont(PdfFontFamily.Helvetica, 20);
    graphics.DrawString($"pdf文件生成测试，第{i}页", font, PdfBrushes.Black, new Syncfusion.Drawing.PointF(0, 0));                
}
MemoryStream stream = new MemoryStream();
pdfDocument.Save(stream);
File.WriteAllBytes("pdf.pdf", stream.ToArray());

生成的pdf有如下问题：

汉字丢失，有未注册的水印

添加注册代码,添加中文字体

string key = "xxxxx";
Syncfusion.Licensing.SyncfusionLicenseProvider.RegisterLicense(key);
Syncfusion.Pdf.PdfDocument pdfDocument = new Syncfusion.Pdf.PdfDocument();
for (int i = 1; i <= 10; i++)
{
    var page = pdfDocument.Pages.Add();
    PdfGraphics graphics = page.Graphics;
    //PdfFont font = new PdfStandardFont(PdfFontFamily.Helvetica, 20);
    PdfFont font = new PdfTrueTypeFont("simsun.ttc", 20);                
    graphics.DrawString($"pdf文件生成测试，第{i}页", font, PdfBrushes.Black, new Syncfusion.Drawing.PointF(0, 0));                
}
MemoryStream stream = new MemoryStream();
pdfDocument.Save(stream);
File.WriteAllBytes("pdf.pdf", stream.ToArray());

中文字体到windows字体里复制即可

再次生成如下图

word与xls或ppt方法类似，此处代码省略，库名见下图