Godzilla vs Kong

After watching both I'm struggling to see how Kong can square up to Godzilla. In skull island, he was big...but not Godzilla big. I think they will try to explain this away by saying that he has had 40+ years to get bigger.

However, Kong's parents were killed by the Skullcralers which Kong then proceeded to kill, this suggests that the majority of Kongs growing is done in the film.... or that his parents were weak?
It's going to be interesting to see how they make this matchup a competitive fight, remember Kong is KING but Godzilla is a GOD.