It doesn't. For that you would need to execute a full headless browser first, extract the HTML (document.body.innerHTML after the page has finished loading can work) and process the result.

If you're already running a headless browser you may as well run the conversion in JavaScript though - I use this recipe pretty often with my shot-scraper tool: https://shot-scraper.datasette.io/en/stable/javascript.html#... - adding https://github.com/mixmark-io/turndown to the mix will get you Markdown conversion as well.