It would be simpler to delete a myostatin repetition from the DNA. Myostatin is a signal protein that stops growth of muscles and encourages destruction of muscles. It evolved to protect from famine, it helps us consume our unused muscle mass when theres nothing else to eat. The more repetitions of the DNA code for this molecule you have is linked to a history of famine for your family/race, the more this molecule is expressed, and the more of a manlet you are. Arabs and Turks have a fucktonne of it, its why they have trouble building muscle mass.
Just delete one repetition of the code and you may increase resting muscle mass for a soldier by 5%. Delete another repetition and you can do more. Eventually you can make humans so muscled, so strong that theycan break their own bones by trying to hard. At that point there are genes you can delete or add repetitions of to make bones stronger.
Its piss easy with CRISPR to make a dude that can punch a Bradley IFV to death or flip Humvees without a problem. In fact a poor country like north korea could do it if they kidnapped a couple of PhDs and bought equipment available on Alibaba.
A fucking mech or exoskeleton is an engineering nightmare by comparison.