Zoro is genius in haki as shown in onigashima where he instantly uses acoc after realising he has coc.
Zoro used all type of haki pretime skip without any training or even knowing about haki.
Knowing where the stone will fall before it fell(ability to see future)- confirmed to be an application of observation haki in wci.
Cutting what you want and not cutting what you don't want -confirmed to be an application of armament haki in wano.
Ashura(showing enemy illusion with your spirit alone)-confirmed to be application of conqueror haki by kaido in onigashima.
zoro is far better genius and has better haki than luffy. It's just zoro didn't get much stronger opponent to fight post time skip to make his haki bloom.
Zoro used all type of haki pretime skip without any training or even knowing about haki.
Knowing where the stone will fall before it fell(ability to see future)- confirmed to be an application of observation haki in wci.
Cutting what you want and not cutting what you don't want -confirmed to be an application of armament haki in wano.
Ashura(showing enemy illusion with your spirit alone)-confirmed to be application of conqueror haki by kaido in onigashima.
zoro is far better genius and has better haki than luffy. It's just zoro didn't get much stronger opponent to fight post time skip to make his haki bloom.