"A normal battery is designed to retain up to 80% of its original capacity at 500 complete charge cycles when operating under normal conditions."
While this is correct, not sure why you did not include the additional information about batteries in the iPhone 15 and higher. The OP told that they have an iPhone 16 Pro.
The complete information reads as follows in the Apple Support document that you referenced:
Batteries of iPhone 14 models and earlier are designed to retain 80 percent of their original capacity at 500 complete charge cycles under ideal conditions. Batteries of iPhone 15 models are designed to retain 80 percent of their original capacity at 1000 complete charge cycles under ideal conditions.
Also note that the document now reads......."under ideal conditions"......not under "normal" conditions.
Either way....."ideal conditions" or "normal" conditions are not really defined.