Database
[{"_id":ObjectId("62622dd73905f04f59db2971"),"array1":[{"_id":"12","array2":[{"_id":"123","answeredBy":[]},{"_id":"124","answeredBy":[]}]}]},{"_id":ObjectId("626230e03905f04f59db29f5"),"array1":[{"_id":"22","array2":[{"_id":"223",/**compare this*/"answeredBy":[]},{"_id":"220",/** and this*/"answeredBy":[]}]}]}]
Query
db.collection.find({$expr:{$gt:[{$arrayElemAt:[{$arrayElemAt:["$array1.array2._id",0]},0]},{$arrayElemAt:[{$arrayElemAt:["$array1.array2._id",0]},1]}]}})