RCS uses the phone network data channel. So more internet than phone in that aspect, it's not at all like SMS hiding in the free space in beacon frames. Therefo

RCS uses the phone network data channel. So more internet than phone in that aspect, it's not at all like SMS hiding in the free space in beacon frames. Therefore coverage won't be any better. The only possible minimal difference would be using authentication via SIM/carrier instead of the Whatsapp method of sending a confirmation code via SMS/call. But that is a very minor difference.