Dictation feature in Outlook allows you to use speech-to-text to author content. It provided a quick and easy way to draft emails, send replies, and capture the tone you’re going for. This feature was available only on Outlook for Windows and Mac desktop clients. Today, Microsoft announced that email dictation feature is now rolling out to iOS devices with EN-US language.
You can download and install Microsoft Outlook on your iOS device from the below link, or you can head over to App Store and search for the app.