Charge slowly.
With the fast charge, the full time is about 1 and a half hours. The previous 5w slow charge, basically takes 3 hours to fill. That's a pretty big speed gap. Then, the difference between fast charging and slow charging is very obvious to the battery, and the fast charging battery is healthy and fast.
Apple 12Promax supports 20 watts of charging, you can use fast charging, does not affect oh, as long as it is the original can be used, see your needs