FYI, you can get most of the same effect on your 13 Pro Max by plugging your charger into a smart plug, and using Shortcuts to make an automation that turns off the smart plug whenever the phone battery goes about 80%.
I use that on my 10th generation iPad and used it on the iPhone X that I had up until about two months ago when it got replaced with a 15 which does support the "charge to 80%" option. It works great.
The only minor annoyance I ran into was that the phones where the OS supports the 80% limit it will occasionally go to 100%, which they say is necessary to keep the battery level indicator calibrated. With the smart plug method you'll have to handle occasionally disabling the shortcut (or charging with the charger plugged straight into the outlet).
Just make sure to pick a smart plug that can be turned off from Shortcuts.
I use that on my 10th generation iPad and used it on the iPhone X that I had up until about two months ago when it got replaced with a 15 which does support the "charge to 80%" option. It works great.
The only minor annoyance I ran into was that the phones where the OS supports the 80% limit it will occasionally go to 100%, which they say is necessary to keep the battery level indicator calibrated. With the smart plug method you'll have to handle occasionally disabling the shortcut (or charging with the charger plugged straight into the outlet).
Just make sure to pick a smart plug that can be turned off from Shortcuts.