Is "so" commonly used to emphasis things? What's the other expression of "so" in this case?
Yes, in this context, the use of "so" is for emphasis. "So" here is another way to say "definitely" or "really", but it gives more emphasis to the adjective here. Not everyone uses "so" in this way, and it is usually more common in certain dialects of English than others. However, using "so" like this sounds like the kind of language that would be used by teenage girls. Ex: You are so going to love the new shoes I bought. Ex: I so want to go to Italy.