Dictate messages on Apple Watch 2

Yes, when you say, "Send message to John Doe"...then continue right on with your message, it will show you a preview of your message. If you're happy with it, you're done. If not, you can click "don't send."

Hi

Yes - to send a message without touching the screen:

Raise your wrist > use Siri (hey Siri, send a message to <whom> saying <what>) > when you have finished dictating, review the message and then lower your wrist to send it.