This might sound silly but can someone actually generate enough force to break a punching bag or you have to be superhuman? My character is enhanced, thought.
No. It’s about wear and tear, poor construction, or improper use, not raw force. If you have a bag in good condition, which is properly set up, you won’t be breaking that by generating too much force.
So, where can this go wrong?
Wear and tear is the big killer here. Punching bags are designed to take a lot of abuse, but that does stack up over time, and they will wear out. Usually you would want to replace your bag when you start seeing damage before it fails catastrophically.
If you’re getting cheap bags, those will wear out much faster, and could could break under normal use. A major place to cut costs is in the shell materials. So, instead of leather, or ballistic nylon, you get nylon, or vinyl. This will start coming apart fairly quickly.
When you’re setting up a bag, unless it’s free standing, you’ll need to secure it to something. It may have a stand, or you may need to mount it into the ceiling. If it’s the ceiling, it needs to mount into a structural hardpoint, like a joist. For heavy bags, this could require holding over 100lbs. (The guildeline is that a heavy bag should be roughly half the user’s own weight.) Simply bolting that into “whatever,” won’t cut it, and the bag will tear free. If you’re lucky, it’ll come down when it’s first hung, though it’s theoretically possible you’d get the balance just right, and tear it out of the ceiling with your first hit.
One possible point of failure here is if a bag was properly mounted, but then replaced with bag too heavy for the rig. It would put extra strain on the mount, and potentially cause it to break.
There’s one specific kind of misuse that can result in all hell breaking loose: Replacing the bag’s stuffing with something much heavier. Most heavy bags are stuffed with scrap cloth (scrap leather is another popular choice.) If someone gets it into their mind that the they should replace it with sand, the resulting bag will be dramatically heavier and rock hard. This means the shell, stitching, mount, chains, everything will be under significantly more strain, and the chances of something breaking are much higher.
So, can you strike hard enough to break a punching bag? Not when you’re using it as intended. However, eventually, it will break, not because you hit it with superhuman strength but because it’s worn out. Punching bags have a fixed lifespan, and you’ll need to replace them as you use them up.