There are ways to do a ring job without removing the engine. But it’s a cheap way just to keep the vehicle running until a proper repair can be done. If you need new rings there’s a chance you have cylinder wall scaring. Just replacing the rings won’t cure that problem.
Without getting into too much detail - You drop the pan…remove the heads…and then unbolt each piston rod from the crank…then push the piston and rod out the top…Replace rings…and put it back in…then repeat for all pistons.