iPhone 11 and Pro have a built-in power management system consisting of a combination of software and hardware that should slow down the aging of the battery.
According to an article on the Apple support site, a mechanism is constantly working in iPhone 11 that prevents aging batteries.
On the iPhone 11, iPhone 11 Pro and iPhone 11 Pro Max, power consumption is dynamically monitored and performance adjusted so that it can meet these needs in real time. This system is more advanced than previous power management systems in the iPhone, and allows your iPhone to reduce the impact on the performance of
Apple notes that the old battery may lead to slowdown of the iPhone, lowering the display backlight, lowering the speaker volume and Internet speed.
Topic: Officially: the iPhone 11 Pro has only 4 GB of RAM
At the end of 2017, Apple was accused of artificial slowdown devices. Apple explained this by saying that the battery gets older over time, so it has to limit the peak frequency of the processor to avoid sudden outages and extend the life of older smartphones. [9to5Mac]