The default search will only return WP posts and pages, it doesn’t specifically search for files within. It searches for plain text in order to get related posts and pages only. If the file reference happens to match as plain text, then that’s good, but the search does not see the match as a file per se. If the search is returning the right pages and you merely need to extract the URLs from shortcodes with title=”search-term” attributes, that could be done with a custom search.php template.

You might try searching for extended search plugins that can do what you want, but I think extracting Google Drive file references might be too specific of a need.

If you end up needing a custom search.php template, this will supplant the normal search functionality. If you still need that as well, you likely need a custom search form for just file searches.

The files are linked through the [google-drive-embed] shortcode for the link to the Google account, The files are then linked using the url=”” of the actual file. Not available as an attachment or post meta.

I’ll have a look around to see if I can find a plugin to do this, have been looking but so far had no luck.

The custom coding I think is beyond me for PHP as I do not know this language.