Yes, both Amps will be created as separate Sonos Rooms. When you choose an audio source to play, you can also choose which Sonos Rooms it should play on.

So it’s possible to play the same music on multiple “sonos rooms”?
 

Also, if I am playing the music on 1 amp connected to 3 pair of outdoor speakers, is it possible to turn off 1 or 2 pairs or do all 3 connected speaker pairs will have to play together? 

Yes, the Sonos App allows for either different music or synchronised across multiple rooms.   The Sonos system, won’t know how many speakers are connected downstream of each Amp. it just controls the audio stream to the AMP.

You can play the same music in multiple Rooms, but unless you have separate hardware volume controls wired in, all speakers connected to an Amp will play at the same time.

Is there any way to turn off some speakers without the volume control hardware? 

No. On an Amp, there is a single set of speaker posts, so the Amp and software have no idea what is connected to those posts. You can mute everything that is connected to one Amp, but without separate speaker controls, you can’t mute a portion of the speakers connected to that one Amp. 

You could install Volume controls for each pair of speakers connected to an AMP.