I haven't done it, but many ice-breakers use a 'find someone who' format. Some of the links given in that other thread will provide example worksheets. You will have to adapt them to make them concentrate on superlatives, with such questions as these:
Find the person in your class who has the biggest dog.
Find the person in your class who has the most brothers and sisters.
Find the person in your class who gets the most pocket money.
.
.
.
The idea is that people stand up and move about, finding out about their peers. The focus moves to the superlative during the follow-up session, when you decide on the most/biggest/most expensive..... (The discussion will obviously
use comparatives - "Alfonso gets more than Rosa" - but you don't have to focus on that.)
¡Suerte!