[{_id:ObjectId("629f2f5e7aa147d6503957d0"),kid_id:"629f2f5e7aa147d6503957ce",inventory:[{size:"0",purchased:"0",used:[{}],_id:"111111"},{size:"1",purchased:"10",used:[{date:"06/08/22",count:"2"}],_id:"222222"}]}]

db.collection.aggregate([{$addFields:{replace:{$first:{$filter:{input:"$inventory",as:"item",cond:{$eq:["$$item.size","1"]}}}}}},{$addFields:{innerObj:{$filter:{input:"$replace.used",as:"item",cond:{$eq:["$$item.date","07/08/22"]}}},innerOthers:{$filter:{input:"$replace.used",as:"item",cond:{$ne:["$$item.date","07/08/22"]}}},replace:"$$REMOVE"}},{$set:{innerObj:{$cond:[{$gt:[{$size:"$innerObj"},0]},{$first:"$innerObj"},{count:"0",date:"07/08/22"}]}}},{$set:{"innerObj.count":{$toString:{$add:[{$toInt:"$innerObj.count"},1]}}}},{$set:{newObj:{$concatArrays:["$innerOthers",["$innerObj"]]},innerObj:"$$REMOVE",innerOthers:"$$REMOVE"}},{$set:{inventory:{$map:{input:"$inventory",as:"item",in:{"$mergeObjects":["$$item",{$cond:[{$eq:["$$item.size","1"]},{used:"$newObj"},{used:"$$item.used"}]}]}}},newObj:"$$REMOVE"}}])