selectedItemColor property
final
The color of the selected BottomNavigationBarItem.icon and BottomNavigationBarItem.label.
If null then the ambient BottomNavigationBarThemeData.selectedItemColor is used. If that is also null, ColorScheme.primary is used when ThemeData.brightness is Brightness.light, and ColorScheme.secondary is used when ThemeData.brightness is Brightness.dark.
Implementation
final Color? selectedItemColor;