When should I change my battery again?
How long does a battery last?
iPhone 11
How long does a battery last?
iPhone 11
You should have the battery replaced when the battery health drops to 80%.
You can check the battery health in Settings>Battery>Battery Health. If it is over 80% everything is fine but if it is less than 80% you should reach Apple Support. Here's a link: Genius Bar Reservation and Apple Support Options - Apple.
When should I change my battery again?