[{"_id":"id1"},{"_id":"id2"},{"_id":"id3"},{"_id":"id4"},{"_id":"id5"},{"_id":"id6"},{"_id":"id7"},{"_id":"id8"},{"_id":"id9"}]

db.collection.aggregate([{"$match":{_id:{$in:["id8","id5","id4","id9","id3"]}}},{"$addFields":{"__order":{"$indexOfArray":[["id8","id5","id4","id9","id3"],"$_id"]}}},{"$sort":{"__order":1}}])