Or the VFX team messed the scale of the 1701-A when they did that shot.
I think it's entirely possible the starbase used in TNG is the same size as the one at Earth, just using larger doors.
On the other hand, making these bases inherently larger wouldn't really be that big of a deal for the Feds.
Since most of their stations and ships are likely modular, they can easily split the construction between several member planets and construction facilities across the Federation and just assemble the thing when it's done (which in their terms could be in a year, or less).
I think it's entirely possible the starbase used in TNG is the same size as the one at Earth, just using larger doors.
On the other hand, making these bases inherently larger wouldn't really be that big of a deal for the Feds.
Since most of their stations and ships are likely modular, they can easily split the construction between several member planets and construction facilities across the Federation and just assemble the thing when it's done (which in their terms could be in a year, or less).