Pregnancy questions/body

So lately I've been thinking about how girls that are really small in that area at least to them have kids vaginally, I'm a senior right now and down the road I want kids but I've often thought about how the hell women that are like 5'4" and about 125lbs push out a baby that's 8-10lbs or something. I'm so terrified of having kids after watching videos about women who end up tearing and the healing process, it's horrible but I've only thought about how maybe I might end up having a C section but I want to know if there are other women out there that have this thought. Probably one of the stupidest things I think about here and there but I'm just pretty curious because nobody talks about it.