Not effectively, no.

First and most important would be the delay between the mic and the Sonos, which would be a minimum of 75 ms. Think of a PA in a stadium. Untenable, especially for longer periods.

Second, in order to have the Roams either grouped (playing the same input) or set up as a stereo pair (playing the right and left input) absolutely requires a Wi-Fi connection. You may have one, since you’ve mentioned it, but it really needs to be there and robust.

As an addendum (rather than editing my last post), there’s really a reason why Sonos doesn’t ever advertise any of their speakers as PA usable. If you search this forum, you’ll see dozens of thread recommending against it, and several cases where people have tried, and failed. You’re much better off renting a wired PA system, designed for this use.  

I rented a PA my Roams are quirky at best most days.