[{first:[{"colorId":"60828a1b216b0972da695f2a","name":"Exellent","description":"Great work"}],second:[{"_id":"60828a1b216b0972da695f2a","colorName":"Green","hexColorCodes":"#2D9D78","sequence":1,"isActivated":true,"created_at":"2021-04-23T08:49:31.729Z","updated_at":"2021-04-23T08:49:31.729Z","__v":0,"isDefault":true}]}]

db.collection.aggregate([{$project:{first:{$map:{input:"$first",as:"f",in:{$mergeObjects:["$$f",{$arrayElemAt:[{$filter:{input:"$second",cond:{$eq:["$$this._id","$$f.colorId"]}}},0]}]}}}}},{$project:{"first.colorId":1,"first.name":1,"first.description":1,"first.colorName":1,"first.hexColorCodes":1}}])