In Windows 10 Build 17618, Sets and Tabs in Windows were introduced. What's disappointing is that in build 17704, sets were removed. This is so they can continue improving it overtime. In Windows 11, maybe tabs in Windows will be reintroduced in the future with a bit of a newer design. If you're on build 17704 and if you want tabs, they were removed in that build and the only way to get tabs back would be to downgrade the Insider build down to build 17686. I hope they reintroduce tabs in Windows 11/10 in the future.