Field of View Setting for the Scan function

Hi all, I am using a fileebox to scan documents with my smartphone to have consistent smartphone positioning for all my scans. The issue I have is that an A4 is not completely displayed on screen when using the nextcloud android app scan function. I compared what the app shows to what can appear on screen when using my samsung camera app. With 4:3 & 16:9, I see the full A4 on screen - when using the “full” setting I obtain the same result as in the nextcloud app. With the Swiftscan app (which I would like to stop using), a full A4 is also displayed.
So my question is: Is there a way to change the camera field of settings used by the nextcloud app so that more surface is displayed on screen?