How to Add relation to default User Class in laravel? - laravel

Question

I'm new to Laravel.
I have many to many relationship with user and movie and hence created an movie_user pivot table:
I am using the Laravel 6.5.2 default authentication; in App/User.php .
The default User.php class is as follows:
<?php
namespace App;
use Illuminate\Contracts\Auth\MustVerifyEmail;
use Illuminate\Foundation\Auth\User as Authenticatable;
use Illuminate\Notifications\Notifiable;
use Laravel\Passport\HasApiTokens;
use Modules\Movie\Entities\Movie;
class User extends Authenticatable
{
use Notifiable, HasApiTokens;
/**
* The attributes that are mass assignable.
*
* #var array
*/
protected $fillable = [
'name', 'email', 'password','profile_pic_url',
];
/**
* The attributes that should be hidden for arrays.
*
* #var array
*/
protected $hidden = [
'password', 'remember_token',
];
/**
* The attributes that should be cast to native types.
*
* #var array
*/
protected $casts = [
'email_verified_at' => 'datetime',
];
}
I want to add a following relationship for movie in user class
public function movies()
{
return $this->belongsToMany(Movie::class);
}
But to do this I think i need to extend Model class and not Authenticatable class;
so the problem is how can I insert the relation inside the 'class User extends Authenticatable'
is there any method like dependency injection to achieve this solution?, and if yes in which is the best way to do this?