Incidentally, it’s probably relevant to (re)read what a Canon exec said on the matter.
We still consider the EOS-1D X Mark III to be our flagship professional camera due to its extreme reliability and confidence it delivers in the hands of professionals. However, it is true that the EOS R3 exceeds the EOS-1D X Mark III in some specifications, to the extent which, by the conventional definition, you could consider it a flagship camera.
While the RF system is a major evolution of the EF system, we believe that in order to bestow an RF camera with the “1” model designation, we must achieve an even greater level of performance, and we continue to work towards reaching those high standards.