I guess the first thing to be sure of is if that's actually how it's being played.
First thing I'd do if I couldn't reach it is see if there's a different way of fingering the chord. For instance, instead of barring the 2nd, 3rd and 4th strings with your 3rd finger, try using your second finger so your pinky can stretch further.
Alternatively, move the whole thing up and do a barred E on the 12th fret instead.
If you're determined to actually stretch your finger... try moving your thumb right to the back of the guitar neck to give yourself more support. and while you're pulling off from the 12th fret, don't feel it's mandatory to keep the 3rd string fingered. You can temporarily mute the string instead.