I feel like panel one has mostly been established already (as in "it's like exercise"), and panel three is something people could safely assume, but I also feel this comic would have been incomplete without those details.
That, and I feel Kevin would have have naturally said "close to," and Nanase would have naturally asked about it. It's IN CHARACTER, darn it!
Seriously, though, "you're not going to get a spell that creates a new planet just because you want it" pretty much sums up how easily the details in panel three are assumed.
Anyway, this is what I'm calling the "Chad" method of getting new, specific spells (see previous commentary). It's possible it's not the only method, but it's the one Kevin (and, by extension, Arthur and associates) is aware of.