While I can perform test automation of web applications in Edge Chromium using Selenium 4 and latest RobotFramework-SeleniumLibrary, legacy IE sites require Edge to be in IE compatibility mode.
I’m not sure how to enable this in Python Robot Framework?
Microsoft have stated how this is done in C# with vanilla Selenium Webdriver here:
https://blogs.windows.com/msedgedev/2019/11/04/edge-chromium-release-candidate-get-ready/