The toilet flange is made to set on top of the floor/tile. If you tile up to it then it will be low and will either need to be raised or add a flange ring adapter to get it up higher. Sometimes a single wax ring may not seal if it is too low and some plumbers add a second wax ring but that should be avoided. Also plumbers do use lead and nylon shims to level toilets if needed. Grout or caulk under the toilet rim is probably a matter of plumber preference.