draggable_withscroll.dart

SizedBox(
      height: MediaQuery.of(context).size.width * 0.75,
      child: DraggableScrollableSheet(
        expand: false,
        initialChildSize: 1.0,
        minChildSize:0.5,
        maxChildSize: 1.0,
        builder: (BuildContext context, ScrollController scrollController) {
          return Container(
            color: Colors.blue,
            child: ListView.builder(
              controller: scrollController,
              itemCount: 25,
              itemBuilder: (BuildContext context, int index) {
                if(index == 15){
                  return Wrap(
                    children: [
                      for(var i in List.generate(7, (i)=>i))
                        Container(
                          height: 25,
                          width: MediaQuery.of(context).size.width * 0.5,
                          color: Colors.primaries[i]
                        ),
                    ],
                  );
                }
                return ListTile(title: Text('Item $index'));
              },
            ),
          );
        },
      ),
    );