https://www.bleepingcomputer.com/news/microsoft/outlookcoms-new-design-is-now-rolling-out-to-some-accounts/

Outlook.com's big redesign is now rolling out to some accounts, and users can look forward to a fancy new look with features like Dark Mode, Emojis & GIFs, and more. The new design brings Outlook.com's interface in line with its Windows 10 Mail app.

The new Outlook experience also comes with the Dark Mode that was teased earlier this month and showed up on some accounts last week. The Dark Mode toggle should appear right under Theme selection in Quick Settings. The updated Outlook webmail design is still rolling out as the company is getting the system ready to migrate everyone over to the new experience.