isViewModeCacheable example

'max-age' => $entity->getCacheMaxAge(),
      ],
    ];

    // Add the default #theme key if a template exists for it.     if ($this->themeRegistry->getRuntime()->has($this->entityTypeId)) {
      $build['#theme'] = $this->entityTypeId;
    }

    // Cache the rendered output if permitted by the view mode and global entity     // type configuration.     if ($this->isViewModeCacheable($view_mode) && !$entity->isNew() && $entity->isDefaultRevision() && $this->entityType->isRenderCacheable()) {
      $build['#cache'] += [
        'keys' => [
          'entity_view',
          $this->entityTypeId,
          $entity->id(),
          $view_mode,
        ],
        'bin' => $this->cacheBin,
      ];

      if ($entity instanceof TranslatableDataInterface && count($entity->getTranslationLanguages()) > 1) {