Thank you for participating in the Watch 4 Beta and for your feedback!
Within Samsung Messages app on the Watch, in the Message composer window, please tap on the text box. Once you tap on that, a keyboard will be displayed. If you swipe up on the keyboard, you will see options for different keyboard settings, as well as a 'microphone" icon to turn on voice to text. Once you set the permissions to "allow", you will be able to use the voice to text function.
