User Data Directories - Restrictions

Good afternoon all,
I was hoping to see if I could shed some light, I have found conflicting discussions in regards to this. So, let’s get straight to it.

If I log in to my next cloud, the only files I am able to see is those granted access to me, I am only able to read, write, or move files within those folders only.
External Drive - (Home Folder)
External Drive - (Departmental Folder)

Expected results
Users are restricted from creating new files that are pointing to the nextcloud internal drive, this is done to avoid drive space complications in the future.

Is there an easy way of doing this? or is this something that is not recommended?