Forms, receipts and homework often have to be sent as a single PDF, while what you have is a stack of phone photos. Add them above, set the order with the arrows and hit Convert: you get one file with one photo per page.
Choose the page size: “Fit” keeps each photo's proportions, “A4” places every picture on an A4 sheet with margins, like a printout. Phone photos are rotated by their EXIF data, so no page ends up sideways.
If the PDF is too heavy for email or an upload portal, resize the photos to 1920 or 1280 px on the long side first. Text on documents stays readable.