[{_id:{genre:"suspense"},price:10210.6,data:[{subGenre:"Thriller",flag:false},{subGenre:"jumpScare",flag:true},{subGenre:"horror",flag:false}]}]

db.collection.aggregate([{$project:{price:1,subGenre:{$arrayElemAt:["$data.subGenre",{$indexOfArray:["$data.flag",true]}]}}}])