Database
[{newDate:ISODate("2022-07-01T11:00:00Z"),timezone:"Europe/London"},{newDate:ISODate("2022-07-01T22:00:00Z"),timezone:"Europe/London"},{newDate:ISODate("2022-07-01T14:00:00Z"),timezone:"Europe/Brussels"},{newDate:ISODate("2022-07-01T07:00:00Z"),timezone:"UTC"},]
Query
db.collection.aggregate([{$set:{newDate:{$dateFromString:{dateString:{$dateToString:{date:"$newDate",format:"%Y-%m-%dT%H:%M:%S.%L"}},format:"%Y-%m-%dT%H:%M:%S.%L",timezone:"$timezone"}}}}])