Database
[{"_id":{"$oid":"62ea84638919f5904e6b6bfd"},"CreatedAt":"2022-08-03T19:17:03.8851421+05:30"}]
Query
db.collection.update({"CreatedAt":{$type:"string"}},[{$set:{"CreatedAt":{$toDate:"$CreatedAt"}}}],{multi:true})