Unread first, read below
This is my first time using outlook.office.com. Coming from Gmail, I liked that I could have my unread emails show up at the top of my inbox, and then have the read emails sorted by date below it. I see that you can filter by unread, but then you can't see the rest of your inbox.
I also love that on Gmail. It's something very simple yet really helpful, I find it very disappointing that Outlook doesn't have that feature.