Hi@akhtar,
You can use Icon Widget to create an Icon in your app. This Icon Widget provides lots of symbols like volume_up, email, etc. I have attached one example below that will create a volume_up Icon.
var MyVolIcon = Icon(
    Icons.volume_down,
    color: Colors.grey.shade900,
  );
  var MyVolUp = IconButton(icon: MyVolIcon, onPressed: null);
  var myappBar = AppBar(
    title: mytext,
    backgroundColor: Colors.amber,
    actions: <Widget>[
      MyEmailButton,
      MyVolUp,
    ],
To know more, join our Flutter Certification Course today.