How can I generate new item list inside my current list when I tap on icon?

Question

can you help me with this? I want to create a widget that can generate a new item list when I click an icon/button.

The widget will be like an uploaded document (many types of documents) section. When the user clicks the current section, it will automatically generate a new section for another type of document for users to upload.

Now, my current problem is when I tap the section, it comes out nothing. Here is my coding. Please refer to it.

class UploadDoc extends StatefulWidget {
  const UploadDoc({ Key? key }) : super(key: key);

  @override
  State<UploadDoc> createState() => new  _UploadDocState();
}

class _UploadDocState extends State<UploadDoc> {

  final List<dynamic> listSelection = [
    { 
      'id': 0, 
      'header':'test', 
      'icon': Icon(Icons.abc_outlined), 
      'title': 'test',
    },
     { 
      'id': 1, 
      'header':'test', 
      'icon': Icon(Icons.abc_outlined), 
      'title': 'test',
    },
     { 
      'id': 2, 
      'header':'test', 
      'icon': Icon(Icons.abc_outlined), 
      'title': 'test',
    },
  ];

  dynamic _selected = 0;
  int index = 0;
  int _count =1;

  @override
  Widget build(BuildContext context) {

    return Column(
        children:  [ 
          Container(
            width: double.infinity,
            height: 30,
            color: Colors.grey,
            child: Row(
              mainAxisAlignment: MainAxisAlignment.start,
              children: [
                SizedBox(width: 10),
                Text(listSelection[index]['header'], style: TextStyle(color: Colors.black, fontWeight: FontWeight.bold)),
              ],
            )),
          ListTile( 
            leading: listSelection[index]['icon'],
            title: Text(listSelection[index]['header']),
            onTap: addNewList,
          ), 
          const Divider(thickness: 1)
        ],
    );
  }

   void _addNewUploadDoc() {  
     if(listSelection.length != _selected.length){
     for (int i = 0; i < listSelection.length-1; i++) {
       _selected.add(listSelection[i]);
     }
     setState(() {});
   }
 }
}

this is my addNewlist()

 void _addNewUploadDoc() {  
     if(listSelection.length != _selected.length){
     for (int i = 0; i < listSelection.length-1; i++) {
       _selected.add(listSelection[i]);
     }
     setState(() {});
   }
 }