Can firstOrNew be used with hasOne relationships

1. Define the `hasOne` relationship in your model:

php
public function phone()
{
    return $this->hasOne(Phone::class);
}

2. When using `firstOrNew()`, pass the relationship attributes along with the model attributes:

php
$user = User::firstOrNew([
    'name' => 'John Doe',
], [
    'phone' => [
        'number' => '555-1234',
    ],
]);

In this example, `'phone' => ['number' => '555-1234']` are the relationship attributes.

3. After calling `firstOrNew()`, you can interact with the relationship:

php
if ($user->exists) {
    // User exists
    $user->phone->number; // Access the related phone
} else {
    // User does not exist
    $user->phone; // Access the unsaved related phone
    $user->save();
    // Phone is automatically created and associated with the user
}

When the user is new (not existing in the database), `$user->phone` will return the unsaved related phone instance. You can then save the user and its related phone together.

By passing the relationship attributes along with the model attributes to `firstOrNew()`, you can efficiently check for the existence of a model and its related model, and create or update them as needed[1][3].