change popupmenubutton size(width and height)

could you plz tell me how to change the size of popupMenu, like to make it wider and bigger, here is my code, thank you a lot. I didnt find some useful info from stack overflow or google...

Widget _threeItemPopup() => PopupMenuButton(
    icon: Icon(
      Icons.more_horiz,
      size: 24,
      color: Colors.white,
    ),
    onSelected: (value) {
      value();
    },
    itemBuilder: (context) => [
      PopupMenuItem(
        child: Container(
            width: 100.0,
            child: Text('Settings')),
        value: () {
          debugPrint('open Settings');
        },
      ),
      PopupMenuItem(
        child: Container(
            width: 100.0,
            child: Text('Flutter.io')),
        value: () {
          debugPrint('goto Flutter.io');
        },
      ),
    ],
  );

You can play with fontSize & padding (top/bottom) to make it bigger.

  Widget _threeItemPopup() => PopupMenuButton(
        padding: const EdgeInsets.only(
            top: 100, bottom: 100), // option 1 : padding on PopupMenuButton
        icon: const Icon(
          Icons.more_horiz,
          size: 24,
          color: Colors.black,
        ),
        onSelected: (value) {
          value();
        },
        itemBuilder: (context) => [
          PopupMenuItem(
            padding: const EdgeInsets.only(
                top: 20, bottom: 20), // option 2 : padding on PopupMenuItem
            child: const SizedBox(
                child: Padding(
              padding: EdgeInsets.only(
                  top: 20, bottom: 20), // option 3 : padding on Text
              child: Text(
                'Settings',
                style: TextStyle(fontSize: 50), // option 4 : play with fontSize
              ),
            )),
            value: () {
              debugPrint('open Settings');
            },
          ),
          PopupMenuItem(
            padding: const EdgeInsets.only(top: 20, bottom: 20),
            child: const SizedBox(
                child: Padding(
              padding: EdgeInsets.only(top: 20, bottom: 20),
              child: Text(
                'Flutter.io',
                style: TextStyle(fontSize: 50),
              ),
            )),
            value: () {
              debugPrint('goto Flutter.io');
            },
          ),
        ],
      );