Yes you can switch from RWD to LR, without current price increase.
You have to use the edit link, as edit option won't appear in your account or contact SA, whichever works.
I have changed my RWD to LR and it is around 5K cheaper than the current price. Delivery date says Oct 2022 to Jan 2023, I'm in Eastcoast so I am not expecting my delivery to be next year in March or May.
I got my ioniq 5 couple months ago, so I am just keeping my tesla order if in case I wanna trade in next year, if not 250CAD not gonna hurt to lose.