Love these over sized pullovers. Really long, cozy, loose knits with simple black accessories. Black and white (or silver) is always a classic. I especially love the open detail in the back of the second one, which would be pretty easy to make.
Knit the fronts and sleeves at a loose gauge with several inches allowed for ease. The back is knit in two pieces. The upper piece is knit with the same amount of ease as the fronts for 10-12 inches with a folded hem. Starting at the bottom of the lower piece, repeat the folded hem, beginning with the same gauge and ease as the rest of the pieces. Then, increase regularly moving toward the top. When seaming, just leave the seam between the upper and lower backs open. The difference in width will create that draping naturally.
Use a fiber that drapes well like plant fibers, like bamboo or cotton, or silk. A longwool would even work here, and you could layer in the cooler months. The loose gauge would also help add more drape.