public function getShipAddress($customerId){
    $customer = $this->_customerFactory->create()->load($customerId);    //insert customer id

    //shipping
    $shippingAddressId = $customer->getDefaultShipping();
    $shippingAddress = $this->_addressFactory->create()->load($shippingAddressId);

    return $shippingAddress;
}

public function __construct(
    ...
    MagentoCustomerApiAddressRepositoryInterface $addressRepository,
    MagentoCustomerApiCustomerRepositoryInterface $customerRepository,
    ...
) {
    $this->addressRepository = $addressRepository;
    $this->customerRepository = $customerRepository;
}

public function getShipCustomer($customerId)
{
    /** @var MagentoCustomerApiDataCustomerInterface $customer */
    $customer = $this->customerRepository->getById($customerId);

    $shippingAddressId = $customer->getDefaultShipping();
    /** @var MagentoCustomerApiDataAddressInterface $shippingAddress */
    $shippingAddress = $this->addressRepository->getById($shippingAddressId);

    return $shippingAddress;
}