update a entity with presave method to avoir a loop

Question

In the hook_entity_update function

update_candidat_from_contrat_direct(Drupal\Core\Entity\EntityInterface $entity)

I call another function in which :

• I create a new node

     $new_entity = \Drupal::entityTypeManager()->getStorage('node')->create([
      'type' => 'candidat',
      'field_nom' => $nom,
    ]);
    $new_entity->save();
  

• I want to attach this $new_entity to the $entity

    $nid = $new_entity->id();
    $candidats_attaches[] = $nid;
    $entity->set('field_candidats', $candidats_attaches);
    $entity->save();
  

But because of the call to "save" function, this involve a new call to the "hook_entity_update", so another call to this sub-function, so a loop....

I understood that there is the "presave" function to avoid this behaviour, but I did not succeed to use it. Can I have some advices, please?