You can use the Text-to-Speech tool for any existing workflows.

1. Navigate to the editor and select an existing published workflow
2. Unpublish that workflow 
3. Select the ellipsis (...) and select Reset workflow
   1. Select Keep a copy of this Workflow. This is a good practice to keep a copy incase you want to return to the original
4. Now you can edit your reset workflow and use the Text-to-Speech tool. Read our article to learn how to use Text-to-Speech