5 MB leaves room for a longer scan when the site allows it.
The target below is already set to 5 MB.
No. The PDF is compressed in this browser and is not uploaded.
The lossless pass and the recompression of embedded images keep the text selectable. If you then turn the pages into images, the text can no longer be copied or searched.
You can download the smallest file that still keeps the text. If that is still too big, you can turn the pages into images. If even that cannot reach the target, the smallest result is shown and can still be downloaded.
Fewer pages, a grayscale scan, or a lower scan resolution all make a smaller file. A photo of a page is usually larger than a text scan of the same page.