I’ve seen it twice in 70mm IMAX 2D and once in IMAX 3D. Something seemed slightly different in the first Rey scene but I can’t be sure - I spent most of that trying to not get a headache so not that reliable.
the 70mm screening expanded to 1.44 but the IMAX 3D i saw was in a 1.9 aspect ratio screen so it did expand but not as noticeably.