What worked for me was returning the modal's content wrapped in a DraggableScrollableSheet:
showModalBottomSheet(
backgroundColor: Colors.transparent,
context: context,
isScrollControlled: true,
isDismissible: true,
builder: (BuildContext context) {
return DraggableScrollableSheet(
initialChildSize: 0.75, //set this as you want
maxChildSize: 0.75, //set this as you want
minChildSize: 0.75, //set this as you want
expand: true,
builder: (context, scrollController) {
return Container(...); //whatever you're returning, does not have to be a Container
}
);
}
)
You can modify this method in the definition of the bottom sheet. Normally, it is 9.0, but as you can see here I changed it to 13.0. 16.0 is full screen.