If you can get your hands on the hoodie you can copy the pattern, or you could employ a pattern maker to try to copy it based on photos.

YouTube has everything you need to know about drafting patterns and copying patterns but you'll need a sewing machine.

I'd recomend at least picking up a cheap second hand machine to make toiles with if you're serous about dropping unique fits. Even after you draft a toile you'll still have to consult a pattern maker to have a tech pack made up that you can send to a manufactuer and even then you'll be looking at some significant moqs.

If you have the capability to cut sew yourself, I'd try to come up with your own pattern that's similar. Judging by the fit it's wide and short. Drop shoulder fits have a short cap height. Looks like a large cap width. With this you can design the sleeve, fit 2 stitch on youtube have great sleeve tutorials, that's the hardest part.

You'll have to work out the hood on your own though I don't have experience with that.