That's a good idea! You can achieve this by adding e.g. &pdf.width=1000px&pdf.height=10000px parameters.

Sometimes you can get rid of the sticky headers with &emulateScreenMedia=false parameter if the page has well implemented @media print rules in CSS. We decided to use page.emulateMedia('screen') with Puppeteer to make PDFs look more like the actual web page by default.

Pages which use lazy loading for images may look incorrect when rendered. &scrollPage=true parameter may help with this. It scrolls the page to the bottom before rendering the PDF.

Using these options make the PDF better: https://url-to-pdf-api.herokuapp.com/api/render?url=https://...