I do not think that would work. Animated or not, Blender or not, your rig is still at the original size and it would deform mesh accordingly.
And would look something like that:

It maybe possible to morph animated model entirely in Blender (because it does support bones scaling on a timeline I believe). And then export character mesh as Alembic.
But I am not a Blender animation guru to advise on a workflow.
Here, some bone scaled on a Blender timeline on top of the animated character from iClone and then exported as Alembic and applied to the same character in iClone (I used a Game Base for simplicity).
Clear disadvantage is, that you have to morph/scale your character in Blender. Maybe good for short transitions.