Something strange. In this video, the guy shows how to bring up the GD archive menu for a selected block, by clicking on the icon if you have Elementor Pro. I have link set to exact time when he clicks on the icon.
https://youtu.be/dFAnC1HQZXg?list=PLdQJXLDS_nIWtLAyS7p8ZNfhOqoAmHsP6&t=186
Well I do have Elementor Pro, but I do not have that icon. As a result, I am not able to insert something extra into an existing block.
I do have a plus sign, which does bring up the GD archive menu, so I can add a new block above or below. But that is not the best solution for editing a template.