[{"date":"15-12-2020","name":"alice","money":7},{"date":"15-12-2020","name":"bob","money":9},{"date":"16-12-2020","name":"alice","money":39},{"date":"16-12-2020","name":"bob","money":25},{"date":"16-12-2020","name":"another name","money":2}]

db.collection.aggregate([{"$sort":{"money":-1}},{"$group":{"_id":"$date","values":{"$push":{"max_money":"$money","the_person_with_max_money":"$name",}}}},{"$set":{"values":{"$slice":["$values",2]}}}])