In radio coms transmitter power does not make much difference to range it is the aerial.
This depends on how well it is matched to the transmitter and the design. In the old cb radios the aerial had to be tuned to get maximum radiated energy. To receive most times a bit of wet string would do. So if short range on transmit the aerial installation may be the problem, standing wave ratio, Aerial length and ground plain all affect the signal take off from the aerial. If these are not good transmitter power make little difference.
With a good aerial a couple of watts can go round the world. I remember when overhead Stapleford talking to some ground station in north west France that was very unhappy I was on their frequency which was the same as Stapleford. When I told them my location they shut up.