Unfortunately, there isn't any current functionality within cPanel or its bundled software that would restrict SFTP users to specific directories. This is due to directory structures of the users stored in
/etc/passwd. As such, I cannot guarantee the implementation of this functionality.
With that being said, you can submit a feature request for this if you would like. Our feature request site is actively reviewed and curated by our development team to identify potential future build plans and accept our community's ideas and suggestions. Adding a feature request here will allow the rest of cPanel's users to vote for it if they would like to see it implemented.
While we cannot guarantee that all requests will be accepted, this is the best way to make suggestions visible to the teams that build cPanel. If you would like to submit a feature request, you may use the "Submit a Feature Request" link in my signature below.
Please let me know if you have any further questions or concerns, and I hope you have a great rest of your day!