No that is a Diplomatic Pod that detaches for Presidential Missions. It is more than twice the size of a Defiant class. But I did use the defiant as a starting point when designing the diplo-pod since I like the Defiants Deflector.
As for the rest of the ships design they wanted a mix of Sovie and Luna in the Design. I think she kinda looks like a Update Excelsior class from some angles.