width property
Width of the minor grid lines.
Defaults to 0.5.
Widget build(BuildContext context) {
    return Container(
        child: SfCartesianChart(
            primaryXAxis: NumericAxis(
            minorTicksPerInterval: 5,
            minorGridLines: MinorGridLines(
            width: 0.7,
         )
         )
        )
     );
}
Implementation
final double width;