Introducing Workspaces in Edge | New feature

GregBurlingame 

If you're still trying to make this work, the reason your command isn't working is because one (or both) of two things; you have existing flags set in edge://flags that are overwriting your argument, or the command you used doesn't work at all. Anyways if you want it to work reset your edge://flags and use my command line, it should work that way. There are some other things I enabled on there that you can disable if you'd like.

mac: "/Applications/Microsoft Edge Canary.app/Contents/MacOS/Microsoft Edge Canary" --enable-features=GlobalMediaControls,GlobalMediaControlsPictureInPicture,TabHoverCards,UnexpireFlagsM90,msEdgeTabGroups,msEdgeTabGroupsAutoCreate,msTabGroupsCollapseFreezing,msTabSearch,msWorkspaces &!

open -a "Microsoft Edge Canary" --args "--enable-features=GlobalMediaControls,GlobalMediaControlsPictureInPicture,TabHoverCards,UnexpireFlagsM90,msEdgeTabGroups,msEdgeTabGroupsAutoCreate,msTabGroupsCollapseFreezing,msTabSearch,msWorkspaces,msRightSideWorkspacesButton"

windows: "C:\Users\[username here]\AppData\Local\Microsoft\Edge SxS\Application\msedge.exe" --enable-features=GlobalMediaControls,GlobalMediaControlsPictureInPicture,TabHoverCards,UnexpireFlagsM90,msEdgeTabGroups,msEdgeTabGroupsAutoCreate,msTabGroupsCollapseFreezing,msTabSearch,msWorkspaces

add ",msRightSideWorkspacesButton" if you want the button to be on the right, but I don't think this works on mac. You can make a .app out of this by using automator. I've uploaded my own https://drive.google.com/open?id=1WVSmDAhJqt-3CdNxKhhcac90KlflVHNc, but you should probably make your own.