A skilled upholsterer can...
A skilled upholsterer can copy the original cushions from photos. There are plenty online. The cushion shape follows the lines of the chair. There are probably closeups of the loops on the upper corners somewhere if you look hard enough (1st Dibs is good for detail shots).
The only thing that might be a little tricky is knowing how much extra to allow for the leather that is taken up by the tufting, but a good upholsterer will know how to do that, too.
If you end up finding a source for these or having one made
I'd be very interested in either having a set made where you did or finding out where you got one! I have a low back chair that needs the cushions and I have been striking out all over trying to find a set. I'd need them in black.
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