It has to be with that name. With a nickname like Wildfire or Conflagaraiton in some translations, it does invoke the image of sheer fiery devastation and with the hell themes he has, it would be very fitting. I thought hte big forest fire earlier in Wano was started by him, but nope it was Kinemon!
Jack was described as leaving devastation in his wake, a "walking calamity" indeed. Queen has shown to cause sheer anarchy, a pandemic panic with his plague type abilities and although I'm disappointed he wasn't a bee zoan or whatever (Killer Bee Queen lol. I also wanted a "Scorpion King"), I think King will cause a massive inferno when he does get to fight.
I have a feeling he will truly fight at Wano itself, after Onigashima has been brought down onto it. And thus King will spread wildfire like that.
I remember Oda Nobunaga using a scorched earth attack at some point in his reign and King might do the same? "Reign of Fire"? Badum tsh lol.