Conversation boost and how to enable it

Hi all. Has anyone been able to enable conversation boost which is one of the new features in iOS 15? I found one website that tells you how to enable it but I don’t see any option to enable it. The instructions they give are to simply, while your AirPods Pro are connected, go to control panel, on the volume control do a double tap and hold to bring up more options and there should be an option to enable conversation boost. On that screen I have the option to change the volume but the option to change transparency mode and spatial audio are greyed out. There is no mention of conversation boost at all. I’ve kept my AirPods Pro connected to my iPhone to see if another update is required. Does anyone know what the current firmware version is for the AirPods Pro? Thanks