NASA is discovering this currently (to their chagrin) with the SLS. The limits are imposed by the strength of the materials used and there are many projects out there currently (Rocket Lab, SpaceX, etc) planning on using carbon fiber, and other, stronger, materials to construct rockets. Since carbon fiber is 3.8 times as strong as aluminium, it seems likely that a carbon fiber-framed rocket could reach a maximum of 1,454ft (based on the dimensions of the Saturn V). I suspect they could be larger than that since carbon fiber is significantly lighter than aluminium and, hence, you could build thicker, stronger frames from carbon fiber. It depends on whether or not you really need a rocket larger than the Empire State Building.
