Apple can make an anti-tracking computer but nothing they do can make an anti-tracking phone. It is a "cell" phone. The very nature of cell phones means the basestations have to decide where you are and which cell takes your connections. With precise clocks and multi-lateration the position of your handset is known to about 50m. All US telco keep this location data (which is constantly updated) for 2 to 5 years. And…
Although for what its worth, I wonder if it's possible for a cell to throw telcos off by broadcasting at higher power and connecting randomly between more and less distant antennas. This is probably one of the dumber ideas I've come up with given that I have no idea how the different protocols for handshakes between cells and towers work. Looking to be educated on it here in the comments.
Cellular modem firmwares are also generally pretty closely guarded and not flashable.