Do iPhones support rSap?

Welcome!

I was not aware of that either.

You are not asking Apple here. This is a community of end users like you and Apple does not share upcoming plans with us.

However, you can leave feedback for Apple showing interest in their supporting that function for Apple by using this link:

Feedback - iPhone - Apple

Are you talking about this?

http://www.android-rsap.com/bluetooth-sim-access-profile.html

Sounds like something where the car has its own cell phone hardware, but uses the SIM and cellular data plan that is associated with a smartphone. I hadn't heard of this before now.