suggestion - maybe give him divine axe rhitta after completing some missions which will him further his strength as he prefers axe type weapons and it can hold his powers easily p
so he hasn't learned the advanced forms yet huh
well, If shanks got serious and used the advanced conquerors haki then MC would've became the Luffy that Kaido knocked out in one hit.
I hope he learns it by the time shanks leaves East blue and ut will be like his farewell gift to him
niceee hope shanks give mc a clue about advance conqueror + armament , also futuru sight as a farewell gift , and dont forget about divini axe rhita too