convert string date to datetime and format

var dateString = "2020-09-25T10:13:21.246321+01:00";
String formattedDateString = DateFormat('do LLLL yyyy').format(DateTime.parse(dateString)); 
// formattedDateString - OUTPUT: "25 September 2020"

string iDate = "05/05/2005";
DateTime oDate = Convert.ToDateTime(iDate);
MessageBox.Show(oDate.Day + " " + oDate.Month + "  " + oDate.Year )

.Net str to DateTime