So many factors, legs, hips, rotation of the core, forearms, bone structure in terms of hands, vicious mentality. So whilst legs play a part a lot of other factors contribute.
Legs are more for balance which helps drive the punch or steer it but the real power is coming from the core because that's generating the actual motion. if legs were actually where power starts from you would see a lot more knock outs because boxers really know how to plant and pivot down when striking but in reality it's the torque of the punch from the waist up generating the motion of what is landing....the hips to the lower buttocks can reinforce a punch but that's secondary. In Wilders case he's punching down most of the time which creates more force but one can see he gets maximum twist in his shots from the waist. Personally I think Joshua hits harder but that's another topic.
This is such an interesting topic since there seems to be such contradictory evidence out there. E.g Wilder and Hearns and Jackson with a sort of whipping, highly leveraged concussive power, against obviously powerful bombers like Tyson, Hamed and Inoue. I don't think a definitive answer to the nature of the source of boxing punch power will be found until AI can really delve into the numerous miriad factors and calculate them. I will say that the most important factor in delivering consistent Kos is timing. I.e. hitting an opponent when they aren't braced or when they are swinging against the incoming punch.
it's voodoo tbh. different power punchers have different ways of generating power. just look at how inoue is destroying his opponents.
Legs and core strength go a long way when it comes to having a dig trust me But not as much as technique and range of motion and proper distribution of body weight If you can’t distribute your weight properly then your punch is going to be useless
You don't need tree trunk legs to generate power but it does come from the legs. Basically sit down on your shots, twist into them and the power generates up through your full body and out through the fist, not just legs alone though but how you transfer the energy, technique, speed, where the punch lands etc.
High jumpers have skinny upper bodies along with their skinny lower bodies so their legs don't need to be huge or powerful to lift that skinny body off the floor. Their bodies are in proportion. Wilder and Wlad have skinny legs compared to their much bigger upper bodies. They are like those guys you see in the gym who focus most of their workouts on their upper body.
Power comes from the ground / Earth up, not just from the legs. That's why it's important to be as grounded / rooted to the ground / Earth as much as possible. This is not only a principle for boxing, but for other martial arts too. Like Judo for example. Power is generated from the ground / Earth when executing explosive moves such as takedowns, throws and punches and etc. When punching, one must imagine as if they are hitting their opponent with the entire Earth. As if the power is coming directly from the ground / Earth below them. And traveling upwards towards their fist. That's why you're better off hitting an enemy with the ENTIRE Earth, rather than with just the fist alone.
There are multiple variables involved in generating punching power. But it all starts with balance and a strong core.