I've been wanting to do this cosplay for a long time, though I'm not sure how to tackle such a detailed shirt. I really want the lace to be accurate.
Any suggestions on how to make it or a pattern that would work for the shirt?
hmmm.... cutwork, that's what that type of lace is called. It's created exactly like it sounds: fancy embroidery is done on a flat sturdy fabric (linen is very common) then sections are trimmed away with tiny precise scissors leaving a beautiful lace. Depending on how good you are at machine sewing it isn't necessarily difficult so much as very time consuming. If I were to make just the cutwork lace around the bottom of the blouse I'd estimate ten to twelve hours in it.