Search for std::literals::string_view_literals site:cppreference.com. Click the third (for me) result, with the title std::literals::string_view_literals:: operator""sv - Reference.
Note that the page 404s. The quotes are URL encoded as %22.
The same query on google has the correct result, which double encodes the quotes in the URL as %2522. I believe kagi is optimistically decoding the URL encoding here where it shouldn't.