This is what I learned from Grammar Book.

We use "too" for negative things and "so" fr both positive and negative things.

Correct: This coffee is too hot (bad thing). I can not drink it.

Correct: This coffee is so hot (bad thing). I can not drink it.

Wrong: She is too beautiful (good thing). I want to have a date with her.

Correct: She is so beautiful (good thing). I want to have a date with her.

But, I feel sometimes American people say "too" for good things. But I am not so sure.

Do people say "too" to refer positive things in American English?