[{"_id":ObjectId("5ed638e566a699750cbb1b0f"),"time":[{"eventCategory":"Audit","objectType":"Audit Log","eventAction":"Query","status":"Initiated","username":"Unknown","userId":"Unknown","timestamp":"2020-05-20T07:19:05.149Z","eventDescription":"Querying without filters."},{"eventCategory":"Audit","objectType":"Audit Log","eventAction":"Query","status":"Successful","username":"Unknown","userId":"Unknown","timestamp":"2020-05-20T07:18:42.232Z","eventDescription":"Querying without filters."}]}]

db.collection.aggregate([{$addFields:{time:{$map:{input:"$time",in:{$mergeObjects:["$$this",{$dateToParts:{date:{$dateFromString:{dateString:"$$this.timestamp"}}}}]}}}}}])