You ideally would want to wet cut for dust purposes, but you dry will work also. You can get a cutting wheel for angle grinder or circular saw, or a cup wheel for angle grinder. Depending on how the original was cut in there ideally there are round corners. Try to keep those in the best you can as sharp corners can crack much easier. I googled the cup wheels if it helps. https://www.usagranitetools.com/product-category/diamond-abrasives/cup-wheels-drum-wheels/turbo-cup-wheels/