Battery replacement for iphone 11

You need a new battery. Get an appointment at an Apple Store or Apple authorized service center to get a new battery.

Yes, it's time for a new battery. And you can use this link to schedule a battery replacement at your Apple Store Genius Bar, which will cost you $89 --> iPhone Battery Repair & Replacement - Apple Support

No, not unless the phone is less than 12 months old and the battery is defective. Your iPhone 11 is well over a year old and the battery is not defective.

Not unless the phone was purchased brand new from Apple or an Apple Authorized Reseller within the most recent 12 months.