#[Route('/index', name: 'index', methods: ['GET'])]
    public function index (): Response
    {
        ...
        $subordinates = $boss->getSubordinates();

        return $this->render('index.html.twig', 
        [
            'subordinates' =>  $subordinates,
        ]);
    }

#[ORM\ManyToOne(targetEntity: self::class, inversedBy: 'subordinates')]
private ?self $boss = null;

#[ORM\OneToMany(mappedBy: 'boss', targetEntity: self::class, orphanRemoval: false, cascade: ['persist'])]
private Collection $subordinates;

...

  public function __construct()
    {
        $this->subordinates = new ArrayCollection();
    }

...

 /**
     * @return Collection<int, self>
     */
    public function getSubordinates(): Collection
    {
        return $this->subordinates;
    }

{% for subordinate in subordinates %}
     
    <div>{{ subordinate.name }}</div>
  
{% endfor %}

$subordinates = $boss->getSubordinates()->toArray();

return $this->render('index.html.twig', 
        [
            'subordinates' =>  $subordinates,
        ]);