You can do that by converting the other date into utc
and then comparing them with isAtSameMomentAs
method.
void main(){
String dateTime = '2020-02-03T08:30:00.000Z';
int year = 2020;
int month = 2;
int day = 3;
int hour = 8;
int minute = 30;
var dt = DateTime.utc(year,month,day,hour,minute);
print(DateTime.parse(dateTime).isAtSameMomentAs(dt));
}