Database
[{"_id":ObjectId("607f4aa55c6c145b61dd4cc5"),StartDate:ISODate("2021-04-21T15:29:30.956Z")}]
Query
db.collection.aggregate([{$match:{$and:[{"$expr":{"$gte":["$StartDate",{"$dateFromString":{"dateString":"2021-04-01T00:00:00.0000000Z"}}]}},{"$expr":{"$lt":["$StartDate",{"$dateFromString":{"dateString":"2021-04-22T00:00:00.0000000Z"}}]}}]}}])