I am wondering if PiHole has the ability to automatically pre-fill as one is typing the host of the local DNS, which has been setup and works. For example, when I type "plex.", I was hoping that it would lookup in its dns table, that plex.my-internal-domain.home' exists so it will automatically add the appropriate https:// prefix or http:// prefix to the local host+local-domain lookup.
Pi-hole has no knowledge of how domains are being used, it simply returns their IP address or a non-routable zeroed out address for blocked domains.
If you're referring to typing in your browser, once you've used the domain once in your address bar, the browser will probably remember it, so later on you can just type a couple of letters and see the entire URL be autocompleted.