The new (in iOS 13) Files app now lets you scan documents and save them directly onto your device or into cloud storage:
Open the Files app. Select the Browse tab. Tap on the three-dot icon in the top-right corner. Tap Scan Documents. Hold your device over the document you want to scan. It should automatically capture the page. You can scan multiple pages into one PDF file. Yu can save to iCloud, or import it into another app.