code: public function isImageOptimizationPixelRatioEnabled()
      {
          if ($this->isImageOptimizationEnabled() !== true) {
              return false;
          }
  
          return $this->_scopeConfig->isSetFlag(self::XML_FASTLY_IMAGE_OPTIMIZATIONS_PIXEL_RATIO);
      }
docs: Determines should Image optimization pixel ratios be used
  
  @return bool