Check out example codes for "box shadow flutter". It will help you in understanding the concepts better.

Code Example 1

new Container(
    height: 200.0,
    decoration: new BoxDecoration(
        boxShadow: [
          BoxShadow(
            color: Colors.red,
            blurRadius: 25.0, // soften the shadow
            spreadRadius: 5.0, //extend the shadow
            offset: Offset(
              15.0, // Move to right 10  horizontally
              15.0, // Move to bottom 10 Vertically
            ),
          )
        ],
    );
    child: new Text("Hello world"),
);

Code Example 2

BackdropFilter

Code Example 3

return Container(
  margin: EdgeInsets.only(left: 30, top: 100, right: 30, bottom: 50),
  height: double.infinity,
  width: double.infinity,
  decoration: BoxDecoration(
    color: Colors.white,
    borderRadius: BorderRadius.only(
      topLeft: Radius.circular(10),
        topRight: Radius.circular(10),
        bottomLeft: Radius.circular(10),
        bottomRight: Radius.circular(10)
    ),
    boxShadow: [
      BoxShadow(
        color: Colors.grey.withOpacity(0.5),
        spreadRadius: 5,
        blurRadius: 7,
        offset: Offset(0, 3), // changes position of shadow
      ),
    ],
  ),

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