Well, 'City of Dragons 2 Graphic Novel' might continue a story from a previous installment. It could explore new dragon characters with different abilities and personalities. It might also show the architecture and culture of the dragon city in more detail, perhaps with some epic battles or political intrigue involving the dragons.
Since it's a graphic novel, it would likely have stunning visuals to accompany the story. 'City of Dragons 2' could focus on the growth and development of the dragon society. There could be a young dragon as the main character who is trying to find its place in the city. It may also introduce some sort of threat to the city, like an external enemy or a natural disaster, and show how the dragons deal with it.
It could be about a city filled with dragons. Maybe it details their lives, the power struggles among them, or how humans interact with these dragons in this particular city. Without reading it, it's hard to say for sure.