You can use iconSize
like this:
floatingActionButton: FloatingActionButton(
onPressed: () {
// Add your onPressed code here
},
child: IconButton(
icon: isPlaying
? Icon(
Icons.pause_circle_outline,
)
: Icon(
Icons.play_circle_outline,
),
iconSize: 40,
onPressed: () {
setState(() {
isPlaying = !isPlaying;
});
},
),
),