The good news is that the February update which brings the new Outlook doesn't strip out the old version of the app, so you ...

This indicates that you have downloaded all your emails from Microsoft Exchange Server to your Outlook account. Note: Unfortunately, this option is not available in the new Outlook app.

Microsoft just announced today that the stand-alone Exchange Server 2016 and 2019 apps will lose their support, along with the other Office 2016 and 2019 apps, on October 14, 2025.