Database
[{_id:1,value:"8 Aug 2022, 1:13 PM"},{_id:2,value:"15 Aug 2022, 1:13 PM"}]
Query
db.collection.aggregate([{$addFields:{tmpField:{$split:[{$arrayElemAt:[{$split:["$value",","]},0]}," "]}}},{"$addFields":{"newField":{"$dateFromParts":{year:{$toInt:{"$arrayElemAt":["$tmpField",2]}},"month":{"$switch":{"branches":[{"case":{$eq:[{"$arrayElemAt":["$tmpField",1]},"Jan"]},"then":1},{"case":{$eq:[{"$arrayElemAt":["$tmpField",1]},"Aug"]},"then":8},]}},"day":{$toInt:{"$arrayElemAt":["$tmpField",0]}}}}}},{$unset:"tmpField"}])