Don’t. Show a web page and open the print dialog, and tell people to save as PDF. All major browsers support this, and the browser HTML to PDF code is the most robust and accurate.

There's nothing in OP's question that suggests this is a one-off operation in response to a user action.

It's very likely to be a massive batch operation of a ton of HTML files that might not even be their own site.

That does make sense where possible. I do feel like OPs question is super relevant if you are doing anything where the PDF has to be rendered server side, like say as part of a larger data process when producing an exportable report in PDF format.