The order you see in a PDF is not painted permanently onto one long document. Its pages are separate objects arranged in a sequence, which means changing that sequence does not require turning the document into images and rebuilding every page from scratch. That is what I work with. Drag a page somewhere else and its place in the sequence changes. Select several pages and they can move together while keeping their order relative to each other. Rotation belongs to the page, duplication creates another reference to work with, and removing a page changes the new document you are preparing rather than the file you originally opened. When you save, I write a new PDF in the order you created. The original stays where it was. Everything happens on your device in the browser. Guides has longer notes on reordering, rotating, duplicating, and organizing many pages at once.