I want to make a very custom user role; i.e. a 'sub admin' if you will. Some things I'd like to do would be to disable the 'html abilities' from within the 'edit page or edit post' mode for this user (they can still edit the page or post normally; just no source code or HTML or CSS access/abilities at all). Another thing I'd like to do is allow access to some plugins/but not others for this 'sub admin'.
I would like to handle this within my custom child theme; as I do not want to modify any core Wordpress files; or even the base theme files.