It’s normal to be nervous, but just think of it this way, millions of people do this every year, and you can to. Probably, when you first started middle school or high school you were nervous too, and then within a week it was comfortable.
You’re going to Oklahoma state, that isn’t quite the real world yet, you will still be in school. Most people have a lot of fun in college, and make friends for life. My money is on you loving it at Oklahoma State.
What are you most afraid of? Leaving your parents? They will be just a phone call away. Leaving your friends? You will make friends fast. Are you living in the dorms? Living in the dorms is like a constant sleepover party. My college friends and I fantasize about retiring and living in a building like a dorm where we can all be just down the hall from each other again, it was great. Are you nervous about getting around campus? Study the map of the campus (I think a real paper map is best, although you can coordinate that with your gps, I found this pdf you can print https://parking.okstate.edu/sites/default/files/maps/MarkUpParkingMap_CW_10122018_0.pdf) and if you’re very worried visit your classrooms a day or two before school starts, do the walk or bus ride from your dorm to class. If you figure out what you’re afraid of, you can address it so you aren’t so afraid.
Act responsibly and everything will be fine. Some kids mess up their first semester by partying too much, not focusing on their studies, and not going to class. Don’t do that. Don’t take this bit of freedom from your parents and go wild. College gives you the chance to make friends with a group that really suits you, you luckily are going to a large university. There is much less peer pressure, because you are an adult now, and you can truly become an automous, independent person. Your peers are adults too, and they know nothing about you, you have no baggage with them.
I bought student season football tickets with my roommate even though I don’t care much about sports. I loved it, it was so much fun sitting in the student section. Maybe that would be fun for you too. I didn’t drink even though many of my new friends did. They didn’t care. In high school I avoided going out with drinking friends, and I was lonely at times, but in college everyone is more mature and less judgmental. You do only what you want to do.
Use the buddy system if you go to parties. Make sure you have a friend with you, and you both watch out for each other.
Don’t overload yourself the first semester. Take at least one class that sounds interesting and fun if you can. If you have any control over your schedule book classes that suit your sleep habits. I hate getting up early, so I booked nothing before 10:00. I didn’t mind eating lunch at other dorms, some kids did. Some kids loved getting classes done early and having the rest of the day. Remember you are on a big campus, so there is travel time to consider. As a freshman sometimes there isn’t much choice though, you can only manipulate your schedule so much.
You’re an adult now, but that doesn’t mean you can’t ask your parents or other adults for help. If you have questions let the adults around you help you, but in the end it will be up to you to do the work.
I’m going to answer your question by saying in my opinion it’s way better out there as an adult than being a kid.