The answer is “you can’t” unless by “multiple era 300” you mean “two era 300”?

Sonos only supports 2 rear effects speakers and they need to be bonded to a soundbar. 
 

Whilst you could group additional speakers to play the tv source there will be a slight delay - 70msec or so - resulting in a kind of echo effect. In addition, and “directional” sound from a 5.1 or Atmos soundtrack will be confused by those extra speakers.