Thank you NJ Quilter for posting here. I believe that the pattern referred to are the ones that have a slight diagonal drawcord and look like
or
I found a couple so called tutorials, that don't have any pictures and looking at the ones above, it kind of looks like the drawcord dimensions could be altered a bit to look better according to the length.
https://www.weekand.com/home-garden/...s-18033641.php
https://homesteady.com/13413893/how-...airie-curtains