Kid and Law being declared Yonko is peak Wano stupidity. Luffy I get, he actually has various countries around the world who are loyal to him. Kid and Law? What islands do they control? Do they even have a single territory that is loyal to them? What about their crews? Neither of them have any relevant underlings, Kid has Killer but Killer’s best feat is defeating a Holdem level fighter.
It took Blackbeard a year of conquering New World territory and amassing military strength before he was declared a Yonko, but with Kid and Law, they have not met any of the criteria to be named Yonko lol.
But I guess the title of Yonko is an inherently meaningless and nonexistent title to begin with, it’s a title based on rumor and ignorant consensus and nothing actually concrete. So in a way, anybody can be a Yonko, even people as unqualified as Kid and Law lol.