A flag in Microsoft's latest Edge Canary build will allow you to open pages in Internet Explorer. It opens the app though, rather than opening the page in a new tab like IE Mode can do.

Click on Default browser. Under the Internet Explorer compatibility section, toggle the button for the Allow sites to be reloaded in Internet Explorer mode option to enable IE mode on Edge.

In Microsoft Edge Insider build version 75.0.109.0 and later, a new experimental flag was added to edge://flags called "Enable IE Integration", which has a description of "Enables hosting Internet ...

How to enable Internet Explorer Mode within Edge Fortunately, the way to enable Internet Explorer mode within Edge hasn’t changed.

In the Microsoft Edge Dev builds, users can now launch web pages in an Internet Explorer tab for backwards compatibility. This launches a web page in a full functional Internet Explorer 11 session ...

Microsoft outlines plans to combine Internet Explorer and Microsoft Edge with IE Mode in a future version of Edge.