how to set showModalBottomSheet to full height

[Update]

In showModalBottomSheet(...) set the property isScrollControlled:true.

It will make bottomSheet to full height.

---

[Original answer]

You can Implement the FullScreenDialog instead.

Flutter Gallery app has an example of FullScreenDialog

You can open your Dialog using below code:

Navigator.of(context).push(new MaterialPageRoute<Null>(
      builder: (BuildContext context) {
        return Dialog();
      },
    fullscreenDialog: true
  ));

Check this blog post too for more:

Hope it will help you.

You can control the height by using FractionallySizedBox and setting the isScrollControlled to true.

showModalBottomSheet(
    context: context,
    isScrollControlled: true,
    builder: (context) {
      return FractionallySizedBox(
        heightFactor: 0.9,
        child: Container(),
      );
    });