[{nId:0,children0:[{nId:3,access:[{permission:"view",email:"user1@email.com"}]},{nId:4,access:[{permission:"view",email:"user2@email.com"}]}]}]

db.collection.aggregate([{"$addFields":{"children0":{"$map":{"input":"$children0","as":"accessInfo","in":{nId:"$$accessInfo.nId",access:"$$accessInfo.access",hasAccess:{"$cond":{"if":{"$ne":[{"$size":{"$filter":{"input":"$$accessInfo.access","as":"item","cond":{"$eq":["$$item.email","user1@email.com"]}}}},0]},"then":true,"else":false}}}}}}}])