In Xodo, you may select specific pages from a document and extract them to a new document.
1. Open the document you wish to extract from.
2. Open the Thumbnails Browser, which is accessible from the bottom navigation bar. If you don't see the navigation bar, tap the center of your screen to bring it up.
3. Select the first page you wish to extract by long-pressing, and continue selecting other pages by single tap.
4. Tap the Overflow menu and then Export button on the top right and select a location to save the extracted file.