Russia is gonna veto any action against Iran at the UNSC, so Israel isn’t looking for UNSC action in calling for the UNSC to convene.

And the US will run cover for Israel, which I suspect is the point of raising the issue in an emergency session. Similar to a vote being raised in congress on a bill or resolution that is known to fail, sometimes the point is just to have the opposition go on record about the issue.

Israel is circling the wagon while domestic pressure for policy change is high.