[{"_id":ObjectId("62441917d12596f96de163a2"),"managerId":1,"reportTypes":[{"reasonId":100,"count":2},{"reasonId":200,"count":3},{"reasonId":300,"count":4}]},{"_id":ObjectId("62441917d12596f96de163a3"),"managerId":2,"reportTypes":[{"reasonId":100,"count":20}]},{"_id":ObjectId("62441917d12596f96de163a5"),"managerId":3,"reportTypes":[{"reasonId":100,"count":5},{"reasonId":200,"count":10},{"reasonId":300,"count":0}]}]

db.collection.aggregate([{"$match":{"reportTypes.0":{"$exists":true}}},{"$sort":{"reportTypes.count":-1}},{"$unwind":"$reportTypes"},{"$sort":{"reportTypes.count":-1}}])