Down stay from heel – Professional Dog Training
This obedience behavior of doing a down stay during heelwork, where you cue a down stay while your dog is at your side and you move forward, is a fun game and the final behavior usually looks quite impressive. This game is great for proofing a down stay and is a great game if you do canine freestyle as well.
You don't need to use intimidation to train this behavior. So keep your tone of voice positive and upbeat. Here is an article on why you might consider using a positive tone of voice with your dog https://dogmantics.com/toneofvoice/
Here is a video from ten years ago on teaching go to the mat, drop at heel and drop on recall using a mat. However, I plan to refilm drop on recall because the video is pixelated. https://www.youtube.com/watch?v=tVGaslyGaGE&t=23s