Chrome version 81.0.3988.0 (released few hours ago) added this new flag
enabling it makes the Chrome UI nearly as big as the new Edge insider's UI (looks even bigger), to make it comfortable to use for touch devices.
Looks like Microsoft's help to Chromium project are bearing fruit, Chrome is a lot more like the Microsoft Edge now. but i think the Edge insider's UI is more appropriate because it's something between the small and big version of Chrome UI :)