Segue o códigoque desenvolvi seguindo a proposta de usar herança e protótipos:
function Client(name, cpf, email, cash) {
this.name = name;
this.cpf = cpf;
this.email = email;
this.cash = cash;
this.depositCash = function (value) {
this.cash += value
}
}
function ClientBank(name, cpf, email, cash, credit, economy) {
Client.call(this, name, cpf, email, cash)
this.credit = credit;
this.economy = economy;
}
ClientBank.prototype.depositEconomy = function (value) { this.economy += value; }
ClientBank.prototype.expandCredit = function (value) { this.credit += value; }
const alfredo = new Client("Alfredo José da Silva", "44455577789", "alfred87@email.com", 300);
const joao = new ClientBank("João Alves", "99955577723", "jojo45@email.com", 300, 500, 900);
alfredo.depositCash(500);
joao.depositEconomy(100);
joao.expandCredit(20);
console.table(alfredo);
console.table(joao);