Worth noting that the Miranda wasn't actually too far off the Connie in terms of size.
No engineering hull, but the saucer has the same diameter and projects back past the circle quite a bit.
It's also pretty thick at the back, not quite sure how many decks but iirc it's about as thick there as the Connie is between the bridge dome and the sensor dome - which over such a large area adds up.
The Miranda is actually significantly bigger in terms of mass/volume, funnily enough.
EC Henry had a great video on this:
View: https://youtu.be/iRSDSJexMEA?si=t6hhZ2QiRysR0LKu