if you can directly transfer someone else's API, you can try this:
https://pdfcrowd.com/web-html.

learn about https://wkhtmltopdf.org/

teacher Zhang wrote an article: http://www.cnblogs.com/shanyo.

C-sharp version, I have used WkHtmlToXSharp and [WkHtmlToXDotNet] ( https://github.com/TimothyKho.
) the former is used by more people than the latter.
be careful not to use WkHtmlToXSharp scheme in IIS, there is a risk of memory leakage, just play casually in the desktop environment;
it doesn't matter if you call wkhtmltopdf.exe directly.

if it is implemented in c-sharp, You can refer to https://www.iditect.com/tutor. to convert local html into pdf

recommend Spire.Doc for .NET API to implement local HTML to PDF. There are free version and commercial version, the commercial version does not have any functional restrictions, you can try it for free. The following is the conversion code, which is very simple, just a few lines.

Document document = new Document();
document.LoadFromFile("InputHtmlFile.html", FileFormat.Html, XHTMLValidationType.None);
document.SaveToFile("HtmlFileToPDF.pdf", FileFormat.PDF);