Google Apps Script - Exporting PDF in landscape format

Question

just looking to customize this code a bit to export in landscape format instead of portrait. Hope there's a simple solution!

function onOpen() {
  var ui = SpreadsheetApp.getUi();
  ui.createMenu('Export PDF')
    .addItem('Export Now', 'exportPortfolio')
    .addToUi();
}


function exportPortfolio() {
  const date = new Date();
  const formattedDate = Utilities.formatDate(date, "GMT+7", "yyyy-MM-dd")

  let dividendPortfolio = DriveApp.getFileById('INSERT SHEETS ID HERE')

  let blob = dividendPortfolio.getAs('application/pdf');
  let pdf = DriveApp.getFolderById('INSERT FOLDER EXPORT ID HERE')
    .createFile(blob)
    .setName(formattedDate + '_DividendPortfolio');
}