Levi's are boxy also. Especially a type 3 trucker.
I"d suggest going with a classic Lee 101. They're not boxy like levi's and more "tailored" than Levi's. an old Wrangler is actually a mix of the two depending on the model you get.
But if you do have narrow shoulders, maybe a Japanese knockoff might be better for your build.
Try them on for sure. I'd suggest vintage, as they're just better in my eye, especially a Big E Levi's.
You can find one for 50 or...