Sort Attachments & Files with a List Page - classic Google Sites
The File Cabinet page and Attachment section in Google Sites does not offer any way to sort the list of files. These instructions tell you how to use a List Page to link to the files and then you can choose to sort..
Since new Google Sites does not offer file cabinets or list pages you there's nothing equivalent in new Google Sites. If you want a sortable Google Drive folder in new Google Sites see: Google Drive Embed - Apps Script
Create a List Page and make appropriate columns on it (e.g. Name, Description, Version plus any others you need) and ensure that one of the columns uses the URL type (the Name column for instance).
Use the Add Item button to make a new list item
use the or existing page link for your URL column and in the search box that appears type a part of the file name you want to link to, or its extension (e.g. .pdf), and use the Search pages button.
Choose the file or attachment you want to link to and use the OK button.
Complete the rest of the columns and use the Save button.
You can then use the List Page's pre-defined sort feature or the dynamic sort to order the list of your files.
Note - Delay in Seeing Uploaded File
There has been reports by some users that there can be a delay between adding the file, or attachment, to your site and it appearing in the page search results: if that's the case then you can right-click on Download and copy the URL of the file, or attachment, (Copy link location in Firefox, Copy shortcut in Internet Explorer, Copy link address in Google Chrome, Copy link in Safari) and add it to the URL column instead of using the search.
If you want to see what you can achieve with this method see our simple example: Example List Page as Front-end for File Cabinet.