We're going through a rebranding, which will affect the name of our app. Everything else about the app will be the same. Do we need to create a new app store instance, or can we modify our existing store with the new name and preview images?
App Name Update
You can modify the name of the app.
Change the display name in Xcode (detailed in this old thread):
https://developer.apple.com/forums/thread/16676
You can also define the display name in Appstore connect. In fact you can even have a different name by country.