Going by the most recent rumor from Max Weinbach, Apple's upcoming iPhone 13 lineup will offer larger charging coil compared to the iPhone 12 family.
There are two possible explanations for the change. The more obvious is that a bigger coil will improve heat management and can allow for higher wattage or in other words - faster charging.
Alternatively the bigger coil could be needed to enable reverse wireless charging - something that Android comepetitors have been offering for a while now.
Stronger magnets for the MagSafe is another rumor thrown around lately and it seems to fall along nicely with the larger coil report.