Negotiated two Apple offers in my career. Different levels, different orgs, different results. Posting what I actually learned because most negotiation advice is too generic to be useful.
What moved:
Sign-on. Every time. Apple seems to have more flexibility here than on other components. Both times I asked once and got an increase of $10k-$20k without back-and-forth.
RSU grant size. This moved when I had a concrete competing offer with a higher RSU number. Not substantially, maybe 8-12% from initial. But it did move. The key was specifics: I told the recruiter the total grant value, not just 'I have another offer.' Vague leverage doesn't work.
Vesting cliff coverage. When I was leaving unvested equity at my previous job, Apple agreed to increase sign-on to partially cover it. This isn't formally a negotiation lever but it's worth raising explicitly.
What did not move:
Base salary. Both times I was told the base was set by level and the offer was already at the top of the range. I didn't push hard because the TC was where I needed it to be, but multiple people I know have said the same thing. If base is critical to you, it may require a very specific competing base figure to move it.
Level. I raised leveling in my second offer (thought I was being underleveled). Recruiter was polite but clear: the offer level was set by the interviewers and wasn't getting re-evaluated post-offer without going through the process again.
Job location. I asked about remote. The answer was no.
Timeline note: My second negotiation took 11 days from initial offer to signed. Apple isn't the fastest, but they didn't rush me either. Don't panic if it feels slow.