Database
[{productId:"c69b7701-c33f-4801-99f3-080450f2b6c7",createdAt:"2021-12-04T17:33:34.221Z",history:[{value:304,storePrice:50,date:1638639214000,prevSold:{price:303,createdAt:"2021-12-04T17:32:50.658Z"}},],_id:"61aba66d9085f0044f96a700"},]
Query
db.collection.aggregate([{$addFields:{history:{$map:{input:"$history",in:{"$mergeObjects":["$$this",{prevSold:"$$this.prevSold.price"}]}}}}}])