The platform does not have the force of law but states the party’s position it wants Republicans in elected office to follow.
Looks like they voted this in their platform not into law. They'd have to somehow manage to change the law that is already being held up in courts that allows carve outs for rape/incest/and life of the mother.
That said I'm grateful this isn't a reality and I hope that the people of Idaho vote against everyone in their party that has proposed and stands behind this.