Generate a pdf file

Hi all,
I have create this simple function for create a pdf:

const createPDF = async () => {
    const response = await Print.printToFileAsync({ 'html': '<h1>Wassup</h1>' });
    return response;
  }

But on iphone, android or desktop the result is: open printer option rathen download the file.
I have wrong the library?
I have try also

  const createPDF = async () => {
    const response = await Print.printToFileAsync({ 'html': '<h1>Wassup</h1>' });
    const pdfName = `${response.uri.slice(0,response.uri.lastIndexOf('/') + 1)}prenotazione_${readableDate.getTime()}.pdf`
    await FileSystem.moveAsync({
      from: response.uri,
      to: pdfName,
    });
    sharePdf(pdfName);
    console.log(pdfName);
    return response;
  }

But nothing changes

Ideally if you can you should always try to generate a PDF file in your server rather then depend on front end since different devices would behave differently. And then fetch that PDF file whenever you need.