$objectManager = MagentoFrameworkAppObjectManager::getInstance();
      $categories = [9];
      $productCollection = $objectManager->create('MagentoCatalogModelResourceModelProductCollectionFactory');
        $Category = $objectManager->create('MagentoCatalogModelCategory')->load($categories);
        $collection = $productCollection->create()->addAttributeToSelect('*')
        ->addAttributeToSort('price', 'DESC')
        ->joinField('category_id', 'catalog_category_product', 'category_id', 'product_id=entity_id', null, 'left') ->addFieldToFilter('category_id', ['in' => 9])->joinField(
                'qty', 'cataloginventory_stock_item', 'qty', 'product_id=entity_id', '{{table}}.stock_id=1', 'left'
            );

foreach ($collection as $product){
     echo 'Name-->'.$product->getName().' Price--> '.$product->getPrice().'<br/>';
  //print_r($product->getData());
}