It would be great to share draft emails between Outlook on different devices including iPhone, iPad and Android. You can start a message or reply on a smartphone and finish it later on a computer.
Sharing drafts between Outlook for Windows or Mac has been possible for many years, only a change from a default setting is necessary. See Share Outlook email drafts between computers
Drafts on iPhone, iPad and Android
These days, the Outlook app for iPad, iPhone and Android will automatically sync drafts across devices and computers. Look in the app folder list for Drafts.
It’s easy to test. Create a draft email on any Outlook (Windows, Mac, Web, Apple, Android) and make sure it’s saved (that should happen automatically). Then check the Drafts folder on another linked Outlook. The number of draft messages should be the same and the newly created draft appear in the folder.
Open the draft message to resume editing it. When you’re finished either save it again or Send.