iPhone 11 is losing charge too fast

shelley ~ 80% maximum capacity is not healthy. Have the battery replaced:

iPhone Battery & Power Repair

About genuine iPhone batteries

Repair Provider Verification

(Articles found by searching Apple's Knowledge Base.)

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If you are saying that the Battery Health / Maximum Capacity, is 80%, then it is time to replace the battery.

About $70 at the Apple Store or authorized Apple Service shop.