Dictation text on watch

When you receive a text message and are looking at it to respond, tap where you see iMessage or Text Message.

When you do that, you should get this new screen.

The microphone appears on the bottom of the screen. If you do not see it there, then check the Watch app on the iPhone and see that Enable Dictation is turned on in General.

There is no way to change the default. However if you receive a message and look at it immediately on the Watch, I remember seeing the dictation microphone appearing right there without having to go through what I showed you. You can provide feedback to Apple if you would like to see that change. Doesn't mean they will necessarily do it, but they will see it there, whereas they don't see the comments here. Go to Feedback - Apple Watch - Apple

You're welcome.