I use the included lightning to usb-c cable to charge my iPhone 12 by connecting it to my macbook pro (2017). I've heard that reducing the charging current is potentially beneficial to the battery. If so, is there a way for me to limit the amount of current available to the iPhone (for example, to the standard 1A)?

Current current data:

  Available Current (mA):   500
  Required Current (mA):    500
  Extra Operating Current (mA): 1900
  Sleep Current (mA):   2400

Solution 1:

There's no need to reduce the amount of current available to the iPhone as the iPhone itself will not draw more power than it needs or more power than is "good for it".

If you still want to do this even though it is not a good idea, you cannot do it on the Mac.