Looks like the locally installed Librera was old -- when I checked earlier, I failed to find such functionality. Since there was a more recent version, I updated
Thanks!
FWIW, it looks like one needs to choose "book mode", not "scroll mode", to be able to select from:
One page
Two pages
Cover, Two pages
Half page
I can see two pages at a time, but I didn't figure out how to accomplish what I was after. For example, if I was viewing pages 5 and 6, navigating to the next view would show pages 6 and 7. Do you know if that is possible?