The new Start menu design is available starting with the release of the Windows 11 build 26200.5641 (KB5060824) in the Dev Channel and build 26120.4250 (KB5060820) in the Beta Channel. However, if the new menu isn't available, it's still possible to turn it on manually using the ViveTool.

As reported by The Verge, Microsoft is improving its Windows 11 Start menu, now available for testers, with more customization options to make scrolling and finding applications easier. These can be sorted into separate categories (as evident in the image below) or used in the classic grid view.