Why Yamato was not designed to fight two Iowas

Could Yamato survive an encounter with two Iowa-class battleships?

Probably not; Yamato was intended to overmatch multiple older standards, not two later Iowa-class fast battleships.

Yamato was not built to defeat two Iowa-class battleships. The Japanese concept sought an advantage over two or more older American standards, while Iowa represented a later and much more demanding opponent. Yamato could plausibly defeat a King George V-class ship, although the British ship might damage upper works before the heavier Japanese guns secured a telling hit. The comparison belongs within the generation of adversaries that shaped the original design requirement.