Removing commands from a specific user

I have a problem, I need to give an access to someone, but the only way to connect to the database is via SSH, so if I have understood everything correctly, I need to create him a linux account (on a Debian 10 machine), the user created doesn't have any right to write in folder, so I guess he can't break anything. But the problem is that he can read any file in the filesystem, I don't really know what is the best practice, I know chmod could fix everything but I don't know if it is a good practice to remove all rights from others and changing the group of every single file to my main linux account. I guess I should remove all the execution rights of the command under the /bin folder and change the group of the file? Thanks for reading! I hope I was clear.