Admin Screenshots for WordPress will add a button to every page in the admin Dashboard, allowing you to take a screenshot of the page you’re on. The screenshot will be saved in your Media Library, and you will get a direct link to it to share. This will let you show how certain settings are, without giving them access to your backend.
If you’re on the other end (like a support agent) and you need to know how someone’s site settings without having to log in, tell your customer to install the plugin, take a screenshot of the page that you want to see, and send you the link.