What "magic" causes "cnn.com" when typed in IE11 to automatically launch Edge (Chromium)?

Question

I just noticed that when I typed in "cnn.com" into the IE11 address bar (Windows 10), that it automatically launched the website in Edge (Chromium) instead, then rendered this bar at the top of the site in Edge.

(it also looked like if this was the only tab in IE, it auto closed IE)

I like this new behaviour to help migrate users over from IE, but sadly I could not detect how this is done code wise by CNN.

I looked in Fiddler, scanned the HTTP Headers, and the meta tags on the site... e.g.

<meta content="IE=edge,chrome=1" http-equiv="X-UA-Compatible">

and the IE only comment tags:

<!--[if lte IE 9]><meta http-equiv="refresh" content="1;url=/2.250.0/static/unsupp.html" /><![endif]-->

but I don't see anything specific that seems to be triggering this? I'd certainly like to entertain applying similar behaviour to some sites/apps that I work on.

FWIW, it also triggers (if you try it enough times) this message to remain in IE11: https://support.microsoft.com/en-us/office/the-website-you-were-trying-to-reach-doesn-t-work-with-internet-explorer-8f5fc675-cd47-414c-9535-12821ddfc554?ui=en-us&rs=en-us&ad=us

Answer 1

Edge 87 installs a browser helper object called IEToEdgeBHO that performs this redirection based on a pre-provisioned site list (https://edge.microsoft.com/neededge/v1)

Inside Edge, see edge://settings/?search=Internet%20Explorer for the setting that enables/disables this feature.