Specs say it will achieve 1.4x magnification and the working distance at that magnification will be about 92mm.
It does not appear to change length when focusing, reviews are starting to appear but seem to be somewhat limited in scope so far - perhaps only including Canon approved topics?? , there's one here that reports working distance at 1x and 1.4x:
Buried deep in the review it's 110mm at 1x and 85mm at 1.4x.
A couple of you tube videos show people using it up close and the lens has not extended wh