I think cats that fear the outdoors were raised as pampered inhouse kitties. I understand it. One of our cats was a kitten raised for a while in a closet, before gifted to us. Our Cat #1 gave her clues about the world. I had a photo of her in a pot from Mexico filled with growing geraniums, but it's not in my scanned stuff now. Rascal was her name.
We had two pure indoor kitties, both females, and they were terrified of the outdoors. One got out, idk how, ans stayed huddled against the front door till we found her in the morning. There are different personalities of cats. You must understand yours to provide their best happiness. We had a few others, (both male and fixed) that could never keep indoors. Tbh? If you want a better chance of an indoor cat, get a female, get her fixed in her first year. You want an outdoor cat, get a male, and fix him too withing his first 6 months. He will still be territorial, but wont be making worthless offspring eaten by worms.