Reduce the file size
The best way to reduce the file size for the scans in Genius Scan is to change the document's resolution when exporting.
Tap on the export button to open the export screen.
On iOS, tap the gear icon to open the export options.
Change the resolution to something lower than Actual such as Large, Medium.
Reducing the resolution will also reduce the quality of your scan. Some trial and error will help you find a good compromise for your use case.