The length of the cage has nothing to do with whether or not a given RD will clear a given size of big cog. It has everything to do with the design of the upper part of the RD. There are older long cage RD's that will not clear a 32T big cog. They can WRAP the chain resulting from a wide range front triple but they may not clear a too big cog. There are now a number of different companies making dropper bolts so a RD that doesn't quite clear a 32T or bigger cog can still be used as long as its cage is long enough to wrap up the excess chain of the lowest allowable gear.