Not much detail as to what speakers, and how you intend to use them, but any Sonos system can have up to 32 speakers, and each ‘room’ in the Sonos system allows you to group them.

I have the 6.1 Sonance system that comes with six 3 inch speakers and a sub. I’m wanting to add two additional of the same 3 inch speakers

That system has nothing to do with Sonos.  Though Sonos does sell and support some Sonance speakers, the 6.1 system is not one of them.  You should contact Sonance directly:

https://sonance.com/