His structure is just super natural, it really embodies how he is as a person. DOOM is the same way.... Of course study, and get enveloped your influences, but to copy would feel like a copy, for me when I started to write stuff or freestyle just by listening to my favourite MCs I picked up a style of my own through that and it's much more natural, but if I straight up tried to rhyme like them It would really feel unauthentic, but that's just my opinion. I'd say look into poetry and see where he's rhyming in verse, is it always the end of the line? is he rhyming the second word of one line with the fourth word of the second? Just play around with some lyrics.