Changing the app name on iOS
To change the app name on iOS, open the project in Xcode, select the project in the left navigation panel, then choose General and modify the Display Name (the first field).
Once changed, re-run the project in Xcode, and you’ll notice the app name has changed.
Changing the app name on Android
To change the name of the Android app, you simply need to open android/app/src/main/res/values/strings.xml file, and modify the app_name value to the new app name.
Now re-run the app, and you’ll notice its name has changed.