$pages->filter()

$pages->filter(string|array|\Closure $field, mixed $args = null): Kirby\Toolkit\Collection

// fetch children with a title starting with 'Project'
$items = $page->children()->filter(function ($child) {
  return str::startsWith($child->title(), 'Project');
});

// fetch children with more than 2 images
$items = $page->children()->filter(function ($child) {
  return $child->images()->count() > 2;
});

// fetch visible children which have visible children
$items = $page->children()->listed()->filter(function ($child) {
  return $child->hasListedChildren();
});