selectionZoomingTooltipTextStyle property
Specifies the text style for selection zooming interactive label.
Widget build(BuildContext context) {
 return Scaffold(
     body: Center(
       child: SfTheme(
         data: SfThemeData(
           chartThemeData: SfChartThemeData(
             selectionZoomingTooltipTextStyle:
                TextStyle(color: Colors.red)
           )
         ),
         child: SfCartesianChart(),
       ),
     )
  );
}
Implementation
final TextStyle? selectionZoomingTooltipTextStyle;