When I tried to start this conversation, my salesman stopped me and said the price on the window sticker is the price I pay. Made me feel good about the dealer I chose.
All you can do now is send an email or text confirming the vehicle will be sold at sticker price with no mandatory add-ons at the dealer. You should also try to nail down your taxes, tags and any dealer documentation fees by asking for your out the door price now. Get it in writing back in either a text or email. You may be able to negotiate the dealer fees if they are outrageous.
Not that this will force their hand at the time of sale if they change their minds, but you should at least get an idea if they are want to play games.
You may also want to request in writing any dealer prep preferences you have such as not installing the front license plate holder and no dealer advertising badges.
You can ask them to not install any accessories when they do the repair order for the pre-delivery inspection. That's what I did and they honored this request.
I also asked them not to install any dealership branding which they didn't, other than the license plate frame, which I switched out when I got my plate.