I would like to know How to charge the iPhone in order to maintain a long life battery health .

These are the very best instructions I know of:

When to charge your iPhone or iPad - Apple Community

Basically, there's not a whole lot you can do to prevent the aging of a battery. Turn on optimized charging and don't worry too much about it. Use the apps you want to use, charge it when it needs charging. Batteries are consumables and will eventually become unusable. At that point, replace them. Meanwhile, don't let a fear of using up the battery interfere with using your phone.

mussab64 wrote:

I would like to know how to charge the iPhone in order to maintain a life long battery health.

About the battery and performance of iPhone 11 and later - Apple Support

Try to not always charge your device to a complete 100 percent keep it between 75 to 90 percent on each charge as a battery tends to lose its capacity after certain charge cycles, it would help you to prolong one charge cycle after charging it twice. Also try to use your device normally as per and try not to always overburden and overheat it constantly with super heavy apps, although the battery health on iPhone 13 Pro Max tends to be very well for its lifetime and you will probably change your device by the time it actually gets in a really bad shape.