Disabling individual sites on a Craft 3 multisite Is there a way to disable non-primary sites on a multisite setup so that users are redirected to a 503 template?

I can't see any configurations that allow me to to this. All sites are either disabled or live.
Seems like this is something you'd do from your .htaccess file or public index.php files for each of the non-primary sites you define.

For example if you have a public_html/index.php for your English primary site and a public_html/de/index.php for your German site, your German one would just header("Location: http://mysite.com/503"); to redirect.