Are those clips on those? That could be the answer you want.

I suspect that is an illusion. I’ll bet they are tacked and folded over. Tricky. Likely hand tacked or done on industrial machines.

It’s simply a loop of self cording( made from the drapery fabric). It’s tacked in the top four corners.

I would draw the thread to join the two corners behind the pleat though to tighten the whole look.

Buttonholes.

I would make the loop like lynartist suggests, but I would first make the pleats using a machine to tack the pleats in place at the top and bottom of the pleats and then hand sew the loop over that to cover the machine tacking.

Personally, I probably would not take on this project myself.

Agree with the others that they are one cord and tacked on and are more decorative than necessary.

That looks like more effort than it may be worth. Just making a panel with those types of pleats is a whole lot of work. Then, you have to have a traverse rod to hang them on if you want to have them functional.

I used to make custom treatments and these large panels were a real struggle.

I do only for myself now and I keep it all as simple as it can possibly be.

That can be done with buttonholes or tacked by hand. For higher ceilings you just need to make your pleats longer and wider so they don't get lost.

Hand tacking would be much, much easier. You are right that the elements are small and the impact may be lost with the height of the window.

The impact would also be lost if the drapery fabric is a print.

It looks nice enough but I, personally, would not do all that. It looks like way too much work.