You would need a 3rd party utility you send the current URL to.
Either a web service using PHP, Python, nodeJS, Ruby or whatever you like that retrieves the TLS cert for the URLs you pass to it. In the easiest way as a GET parameter, encodeURIComponent can be in handy for this. You can also run this service locally on your computer, so you don't need a hosting provider.
Or a local CLI tool on your machine like this or that you communicate to via a helper program using Native Messaging.