Probably 80%-90% of 13-2 is its own story. One of the main characters was a side character and largely uninvolved in the original. The other main character is an original character. The enemy is original. The very ending is relevant, but summed up with a little bit extra.
The biggest thing you’re missing out on is the context of random characters from the first game showing up in the second.
I live in a maroon state. I’m definitely overweight, I literally just checked a BMI calculator and apparently I’m a hair away from obese (that doesn’t feel accurate, but that’s what the numbers say).
I’ve been told so many times that I’m a healthy weight and I don’t need to lose weight.