headerTextStyle property
Specifies the calendar header text style.
Widget build(BuildContext context) {
 return Scaffold(
   appBar: AppBar(),
     body: Center(
       child: SfTheme(
         data: SfThemeData(
           calendarThemeData: SfCalendarThemeData(
             headerTextStyle: TextStyle(color: Colors.purple)
             )
           ),
         child: SfCalendar(),
         ),
     )
  );
}
Implementation
final TextStyle? headerTextStyle;