Finding log in credentials for signal and FB messenger

Hi guys,

Im trying to understand if it is possible to obtain the log in credentials user for Signal and FB messenger apps if both apps were deleted on an iphone 7 ios 13.3.1? When looking in settings/ password there is nothing saved under autofill which I was hoping for.

Is there any way to obtain this with a logical extraction or would it require a file system extraction? Or is it simply not possible?

P