code: private function readPrintGridlines()
      {
          $length = self::getUInt2d($this->data, $this->pos + 2);
          $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);
  
          // move stream pointer to next record
          $this->pos += 4 + $length;
  
          if ($this->version == self::XLS_BIFF8 && !$this->readDataOnly) {
              // offset: 0; size: 2; 0 = do not print sheet grid lines; 1 = print sheet gridlines
              $printGridlines = (bool) self::getUInt2d($recordData, 0);
              $this->phpSheet->setPrintGridlines($printGridlines);
          }
      }
docs: Read PRINTGRIDLINES record.