allow opening multiple Outlook instances (e.g. one screen with Calendar, second with mailbox)
Back on Windows I always had two Outlook Windows open - one with mailbox, the second with calendar. Was really practical to be able to scroll through the calendar when writing an email and looking for possible slots to suggest a meeting/phone call/ etc. On Mac this does not seem possible.
Kedar Raybagkar commented
Rather than this I would suggest to have a DASHBOARD feature that shows all in one glance/page.
On Mac, go to File>New>Main Window.
File -> New -> Main Window