[{"_id":"1","Email":"driver1@example.com","Subscriptions":[{"Id":"sub1","PartnerId":"123"},{"Id":"sub2","PartnerId":"456"}]},{"_id":"2","Email":"driver2@example.com","Subscriptions":[{"Id":"sub3","PartnerId":"789"},{"Id":"sub4","PartnerId":"123"}]},{"_id":"3","Email":"driver3@example.com","Subscriptions":[{"Id":"sub5","PartnerId":"456"}]}]

db.collection.aggregate([{"$match":{"Subscriptions.PartnerId":"123"}},{"$addFields":{"Subscriptions":{"$filter":{"input":"$Subscriptions","as":"subscription","cond":{"$eq":["$$subscription.PartnerId","123"]}}}}}])