In college you won’t be able to be a professional ballerina, but I think you will be able to do the ballet for fun and exercise. In my adult classes sometimes people started at age 40+. adult beginner classes are more relaxed, and most everyone is their for exercise not perfect form.
What you probably don’t realize if you have never taken a ballet class is when we point our foot is towards the side. For instance if I extend my leg in front of me and point my foot, the top of my foot is not towards the ceiling. My foot is almost resting on my pinky toe, which allows for an easier extension of the foot then trying to point straight forward. Does that make sense? If you are just pointing forward it might feel impossible to you with very flat feet.
Ballet will help with every type of dance, and swimming and diving, and all sorts of things.
One warning, if you are not very flexible be warned that some teachers do floor stretches at the beginning of class before warming up, which I basically can barely do. Be careful not to pull anything. It is completely unnessary to stretch before class in my opinion. However, always stretch after to avoid muscle soreness.
Ballet positions are mostly in Fench, so you might want to know the basics, just to feel a little ahead of the game when you start. Plus know the 5 positions. There must be youtube with the basics. No matter what the teacher will show you what to do, she won’t just call stuff out if you are a beginners class.