Domain (site) management is in the hosting control panel DirectAdmin, in the “domain settings” section
To add a site, click on “add new” and in the window that opens, specify the name of the site (domain) and its parameters.
If you specify a traffic limit, then when the site reaches this limit, it will be disabled. If you want to use restrictions as for the main account, just leave the checkboxes and do not specify the limits separately.
You can disable PHP or SSL access in the options by unchecking the appropriate checkboxes.