One additional thing to mention to the owner is that a regular sized wax ring might not be sufficient to close the gap between the closet flange and the toilet connection. Closet flanges (the opening connection to the drain pipe) are typically installed to sit flush with the subfloor. If multiple layers of flooring have been added after that or if tall tiles are used and the toilet sits on top, then it increases the distance between the toilet connection and the flange. There are taller wax rings that can be used for these situations.