File vs Smart File

Possibly you mean Smart Folder? If so, see the following excerpt from Create or change a Smart Folder on Mac - Apple Support

You can create a Smart Folder that contains a list of files that have something in common. You specify the criteria for the items you want in the folder, such as the type of file, the date a file was opened, or the contents of a file. For example, if you like to bake, you could create a Smart Folder that has all the Pages documents you opened in the past year that contain the words “cookie” and “recipe.”

As you add, change, or delete files on your Mac that meet the criteria, the list of files in the Smart Folder is updated automatically.

A Smart Folder is a saved search query. The Finder presents it to you as an icon that looks similar to the icon of a regular subdirectory. When you open the Smart Folder, what you will see is a dynamically-updated search result – as though you had done a new Find. iTunes/Music have a similar concept called Smart Playlists.

According to Wikipedia, Macs first started offering Smart Folders in April 2005, with the release of Mac OS X 10.4 ("Tiger"). An Apple Wiki says that iTunes got Smart Playlists in July 2002 with the release of iTunes 3. While both features might have been inspired by similar features on other platforms, it seems likely that Smart Playlists would have been part of the inspiration for Smart Folders.