User.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class User extends Model
{
    /**
     * The booted method of the model
     *
     * Define all attributes here like normal code
     *
     * @param  string  $value
     * @return string
     */
    protected static function booted() {
      static::retrieved(function($user) {
        $user->first_name = ucfirst($user->first_name);
        $user->phone_number = $user->country_code . $user->phone;
        return $user;
      });
    }
}