Yes, of course. Connect via analog/RCA or digital/coax. Since many Bluetooth transmitters only accept digital via optical you may also need a coax-to-optical converter. They’re inexpensive. 

Thanks for the reply! I am a newbie to all of this! Do I connect a coax to optical converter to the digital out on the back of the Port and then connect a Bluetooth transmitter to that?Thanks!

Why would you do that? The Port can do the conversion for you. Just use the analogue outs on the Port and connect those to your bluetooth transmitter.

To avoid going through an unnecessary conversion to analog and back to digital perhaps? It's a matter of taste, but I personally use a coax to optical converter to feed a Bluetooth aptX-HD transmitter. 

We are using the analog outputs on the Sonos Port. So could I just connect a bluetooth transmitter to the digital out? Thanks!

Yes.