Hello Nancy2019
Hi, I'm Karl and will be happy to help you today.
First, just so there is no misunderstanding, this is a public user-to-user support forum. We're users helping other users. We do not work for Microsoft and have no input on Microsoft's policies, procedures, or design decisions.
At some point, the "new Outlook" is going to completely replace the Windows 10 / 11 Maiil app. At the current time, as you have discovered, the "new Outlook" does not support POP accounts.
With that said, if you are launching the "new Outlook" by clicking on the Mail icon in the Windows 10 / 11 Start menu, yu should see the ""new Outlook" toggle in the top right. Yu will not see that toggle if you explicitly launch "new Outlook" by clicking on the "Outlook new" icon
For your info
Things to look forward to in the new Outlook for Windows https://techcommunity.microsoft.com/t5/outlook-blog/things-to-look-forward-to-in-the-new-outlook-for-windows/ba-p/3975602
If you have any questions, don't hesitate to ask, we're here to help you further if needed.