How Resize PDF pages works
PDF resize scales every page of a PDF to a standard paper size, A4, Letter, Legal, A3 or A5, or to a custom percentage of the original dimensions. It recalculates the page dimensions and rescales the content proportionally so the result prints or displays correctly at the new size.
This is useful when a PDF arrives in a non-standard size and you need it to match a print run, or when you want a compact A5 version of an A4 document for reading on a small screen. Native vector content stays sharp at any size because it is rescaled mathematically; raster images are scaled too, so they can soften if you enlarge significantly.