how to use object in another php file?

Question

 class Conn           // No parent db class - it serves no purpose
                         // Class names begin with capitals, by convention
    {
    
        private $host;   // Local copies of database credentials. Not really needed
        private $user;
        private $pass;
        private $dbname;
    
        // Set up the database connection in the constructor.
        public function __construct(string $host, string $user, string $password, string $dbname) {
            $this->host = $host;
            $this->user = $user;
            $this->pass = $password;
            $this->dbname = $dbname;
    
            // Set mysqli to throw exceptions on error
            mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);

            // open a connection for later use
            $this->conn = new mysqli($this->host, $this->user, $this->pass, $this->dbname);
        }
    }
    
    class Work extends Conn
    {
    
        public function insert_user(string $email, string $password_hash)
        {
            $sql = "INSERT INTO user (email,password) VALUES (?,?)";
            $stmt = $this->conn->prepare($sql);
            $stmt->bind_param('ss', $email, $password_hash);
            $stmt->execute();
            return;
        }
    }
    
    
    
    try {
        $obj = new Work("server", "username", "password", "schema");
        $obj->insert_user('user@example.com', 'asdfasdf');
        echo "inserted";
    } catch (Exception $e) {
        echo $e->getMessage();
        }

I have this code in class.php file . How can I use this page $obj in another file. Like I want to use $obj in prcess.php file. How can I do it now?