Today, Microsoft has started rolling out a new set of updates
to its Office apps on iOS to those enrolled in the Insider program. The new builds include a few improvements, most of which target Outlook. For starters, there's now support for shared mailboxes and calendars, so you should no longer need to use a PC to see your content in shared accounts. There's also a bit more security thanks to S/MIME support, allowing you to sign and encrypt your e-mails. Finally, you can mark individual messages in a conversation as unread.
The remaining Office apps didn't get quite as much attention, but Excel did get support for Dynamic Arrays. The feature was announced last month and rolled out to Windows and macOS, but now iOS users can also use new formulas to return results into more than one cell. Meanwhile, PowerPoint can now open PowerPoint presentations into a view optimized for reading without first having to open the presentation in Edit mode.
If you're enrolled in the Office Insider program and you have a compatible iOS device, the updates should be available to you on the App Store right now. Otherwise, the new features should make their way to you later this month.