//Refer-doc:https://fullcalendar.io/docs/contentHeight
var calendar = new FullCalendar.Calendar(calendarEl, {
  contentHeight: 600
});
//or

var calendar = new FullCalendar.Calendar(calendarEl, {
  contentHeight: "auto"
});

//You can dynamically set a calendar’s contentHeight after initialization:

calendar.setOption('contentHeight', 650);