Most planes are made of cast iron and that is normally brazed. I have seen some good plane repairs and lots of bad ones. Sometimes, depending on where and how bad the damage is, the plane can be used without repair. If the break goes through the mouth then it will probably flex during use which will probably render it useless except for replacement parts. I would have to check it over closely to determine if the event that caused the obvious damage didn’t cause additional, not so obvious damage such as a warped sole. Any brazing is definitely best left to someone with a well developed skill set in working with metals.
Obviously, the more common the plane is, the less effort could be justified in trying to restore it.