To give access to your developer, you have a few options available.
First option: Provide the main Cpanel logins for the relevant account to give full access to the data. Note that you can't generate a separate Cpanel user, only the main one for the relevant account will work.
Second option: Provide access only to the site content (using FTP) and the database.
You can check here how to create a separate FTP account:
You can check here how to provide separate database access
Updated 8 days ago