It's not possible to change the graphics mode on the iOS port of SCUMMVM. The only one available in the gui is "default", which looks really blurry on an iPad. Please add 1x, 2x etc options with nice blocky pixels, integer-only scaling.
There should be a "blocky" scaling mode available now, i.e. no filtering.
There is! Looks beautiful crisp now!
Thanks a lot!