I successfully changed my react native package name using the commands below. Very easy to use.
npx react-native-rename "JustQuiz" -b com.boltskills.appname
You should get some information similar to this
Bundle directory was not changed. Keeping...
Done removing builds.
APP SUCCESSFULLY RENAMED TO "JustQuiz"!
Podfile has been modified, please run "pod install" inside ios directory.
Please make sure to run "watchman watch-del-all" and "npm start --reset-cache" before running the app.