Database
[{"_id":{"name":"xyz","Rollnumber":123},"Stats":[{"subject":"Maths","Examdate":{"$date":"2020-08-23T00:00:00.000Z"}},{"Subject":"English","Examdate":{"$date":"2020-08-24T00:00:00.000Z"}}]}]
Query
db.collection.aggregate([{"$match":{"_id.name":"xyz","_id.Rollnumber":123,"Stats.Examdate":ISODate("2020-08-24")}}])