Star level is determined by your island's layout and is most likely determined on load and not something that can be set with a flag.
Terraforming
is something you can set with a flag, though. I will give you some suggestions on what to change, but
make a backup before changing anything because if I'm not 100% correct and missing specific things to make the game "legit" and undoing the flags won't fix it, you're out of luck.
Code:
083 - TotakekeTalkBeforeFlag = 1
632 - TkkFirstLiveJoined = 1
813 - StandByRcoVisitMyHomeAfterTkkFirstLive = 1
This skips the entire process of seeing the KK show in general and acts like its immediately after you see the concert with Tom Nook giving you the terraforming app. You can then buy all the permits from the Nook Stop as normal.