I am going against the grain here, but sitting exams, choosing subject, forging a life plan are adult situations and many of our young people's brains are struggling to adapt. I don't think using techniques, like removing privileges, are going to be effective and with so few weeks until exams it's going to generate stress and conflict with everyone. Unless of course these things are the reason he's not revising. I suspect it is more complicated than that. Taking away those things might drive him to revise but what will the quality of that revision be like? You need to find a way to make him want it for himself.
Sit down with him and ask him what he is finding hard about revision. It might not be laziness, it might be. Find out what his fears/motivations are and use that knowledge to work with him. Talking to him as an equal goes a long way, even when internally you are screaming inside.
Agree some tools, like a slot (slots) in the week that is dedicated to revision. Start small and build from there.
Use Chat GPT to come up with a study plan.
Is there some treat or something he wants that he will get if he meets all the study requirements you set for him?
I have a 15 yr-old who is similar, and his school has been especially bad at encouraging independent study and homework throughout his schooling, so he has know real grasp of the level of work that needs to be done. I also think there are some anti-education narratives on social media that don't help boys' motivation.
I approach as a micro manager and sometimes it feels like whack-a-mole. He steps up in one subject only to discover he's started to slip in another. It is so hard! I am extremely stressed and worried about the exams but we have worked out a plan for him for beyond the exams that is achievable, and I have to learn to let go of some of my expectations.