Kaido wanted to start large-scale war supposedly to die in a grandiose way kinda like WB did, but ironically, he's been beat without even the Wano folk he's oppressed for 20 whole years witnessing it & is now dying in the same way Oden died (i.e. by boiling), no grand scale purpose in sight and with no one to witness it.
I can understand why characters like Kaido and Linlin dying by boiling Lava would raise some eyebrows, but then again the same Kaido that fell from a friggin sky island and walked off with only a slight head ache was being hurt by slams on the rooftop lol and Oden who is an anomaly akin to Linlin also died via boiling so it's feasible. Narrative-wise this death makes sense as underwhelming as it might be for some.