How to create a round CheckBox in Flutter ? Or change the CheckBox’s style , such as selected image in Flutter?

The Material Design checkbox has a shape property and you can set CircleBorder() to it and it will be round.

Checkbox(
      checkColor: Colors.white,
      fillColor: MaterialStateProperty.resolveWith(getColor),
      value: isChecked,
      shape: CircleBorder(),
      onChanged: (bool? value) {
        setState(() {
          isChecked = value!;
        });
      },
    );