Hello Peter,
Thank you for the question.
While, given normal conditions the device accuracy is withing 3meters. I would say that good radius is 10meters for personal estimation and device should report the position within this circle. 99+% of the time.
There is no command for such parameter. Whats your application and why do you need it?
Remember that the measured location is a result of constantly changing conditions (moving satellites/moving car/objects nearby that impact the signal.). Therefore, it's a matter of change, even if you knew the accuracy you only know the circle and at best probability where the estimated location point is most likely to appear.
Please find additional information here:
http://blog.oplopanax.ca/2012/11/calculating-gps-accuracy/
https://stackoverflow.com/questions/29301909/how-to-calculate-gps-accuracy-in-meters-from-nmea-sentence-information
If you have any further questions don't hesitate to ask. Alternatively, upvote the answer if it provided a solution to your question.
Stay awesome and have a great day. :)
Best regards,
Vytenis