I’m looking to tell the browser that a website search can be used by the browser as a search engine

Ultimately what I’m looking to achieve is is the Open Search Description.

Already covered in another topic, the reason for my question is because this was answered 14 years ago, I’d like to know what the best practice is, if not the same as above, to achieve the same results.

Using many of the links on previous questions, such as howto, are 404. Even the XML A9 namespace is a 403 link.

With a rapidly changing world it would be good to understand what the modern way to achieve this would be.

I’m using jQuery, Html, PHP