With “technique and surprise”, yes, a small woman can take down a larger man. Surprise, or an unwillingness of the man to actually cause pain, can give that result.
But soldiers don’t tend to be caught by surprise, and they tend to have training. In combat, hand-to-hand means someone is about to die.
Before deploying to Afghanistan in 2007, the Army gave demos of how to control a prisoner. I lucked out and had the 5’2” female MP demonstrate on me. After, she asked if I had any questions.
I pointed out a crowbar within easy reach, and said if it had been for real, I’d have grabbed the crowbar. “But that isn’t the point!”, she said.
I said it was. A wrist lock works great, provided you get to put someone into it, and that person isn’t trying to kill you. But in a real fight, very few people will allow you to lock up their wrist, and some will accept a broken wrist in exchange for busting your head. A suicide bomber suspect may not worry about what happens after he crushes your skull.
My ex-Marine daughter could probably take me down - but then, I wouldn’t be willing to kill her.
Some years back, I was in a martial arts class where the blackbelt female instructor got upset when a 200+ lb guy (blue belt) said a technique wouldn’t work. She said she could clobber him, and he said only if it wasn’t full contact. She said she would demonstrate, full contact.
During the first 10 seconds, she landed several kicks. Then he hit her in the stomach, and she dropped on the ground making strange sounds. It took 5 minutes before she could stand upright.
I’m not insulting women. I’m a 5’7” guy. But if I get in a fight with a 6’2” guy who knows what he is doing, he’ll take me apart. There is a reason boxing and martial arts have weight classes. If training is equal, or even close, the guy who is 50 pounds bigger wins. Not 100%, but way too close to it for my comfort.
A coworker of mine once told me she could kick my a$$ because she was trained in kick boxing. I had 8” and 100lbs on her. I told her if it was a true fight, and she was unarmed, she would die.
Her instructor confirmed it. Technique has its place, but size beats it.