the datetime module is your friend. You seem to be dealing with a date-time stamp in ISO format. The datetime module has a class method to generate a datetime object from an ISO formatted string.
from datetime import datetime
dateinput = "2021-03-01T21:21:00.652064Z"
stamp = datetime.fromisoformat(dateinput)
But here you will get an error because the trailing 'Z' is not quite right. If you know that it's always going to be there, just lop off the last character. Otherwise you might have to do some string manipulation first.
stamp = datetime.fromisoformat(dateinput[:-1])
See also the strptime() class method to get datetime objects from arbitrarily formatted strings.
Hoping this helps...