Microsoft is preparing to change the Outlook app and the preview is now available. There is not a set date for the full implementation of the new Outlook app.
This will only affect the Microsoft 365 Outlook desktop app. The web app is not changing. If you choose to try the new Outlook app, it'll take a few minutes for it to download and set up. It will look similar to the Outlook Web App. Once it's set up, you can easily toggle between the new and old views.
Get a sneak peak at the new app!
You do not need to take action at this time; downloading the new version is optional. It is supported by IT, and assistance is available from the IT Service Desk.
If you want to try it out, click the button in the upper right corner of Outlook and follow the prompts to download and set up the new one. Click the Microsoft link at the end of this article titled, New Outlook for Windows if you want to learn more.