This is a trained soldier with wrestling, grappling, and mixed martial arts experience for years. I could accidently hurt a lot of ZKKboys without even trying so it would be better if you never see me in real life.
Bro, height and arm length matters only a little. Daniel Cormier is 5'9, and he is one of the strongest people in the world when it comes to hand to hand combat, he can beat up a lot of people who are 6'4 and above with ease. Your weight and your conditioning matters much more. I am 6'1 and 190 lbs and I can punch hard, if I hit a guy who is 180 lbs, he will probably get KOed with 1 punch. If I hit a guy 230 lbs, he can take more than 1 punch depends on how tough he is, then that depends on how good 230 lbs guy's conditioning is, if I get him tired by fighting from outside, or using grappling to got his back or put him in a guillotine choke, or arm triangle etc, he will get tired easily if he doesn't have conditioning for fighting, then his weight doesn't matter as well, because he will gas out quickly.