Lots of other replies so hopefully it makes sense but just to be clear: 'the' Schwarzchild radius isn't one specific number, it's based on the mass of an object

Lots of other replies so hopefully it makes sense but just to be clear: 'the' Schwarzchild radius isn't one specific number, it's based on the mass of an object. Every massive object has a different SR (also called its Event Horizon), and if you compress the object entirely to within that radius, it will become a black hole. It's just a measure of how small the object needs to be before light cannot escape its surface.