This has been covered many times. The answer is: it depends what sort of dealer you have.
When I ordered my Enyaq in December, the prices came down in January, but my dealer said “he shouldn’t really do this” and pushed back.
However, I’ve since changed to an Ioniq 5, and my dealer told me very clearly that if the AP went down, he would resubmit the order.
As far as I understand it, Motability don’t encourage this.