I'd like to see the feature like vBulletin where you can create attachment extension and give permissions based on groups (which groups are allowed to use and the file size limits etc)
Control upload limits for attachments, avatars, and profile banners based on user permissions. Features 📂 Attachment Constraints Limit max count, size, width, and height per message. Node-specific permissions for posts via forum permissions...
xenforo.com
There is no extension-based permissions (and seems permissions system is not good for it), but i can add option with list of groups and allowed file extensions if someone really interested in.