Hi, Apple does not permit a single slider to enable 2000 nit brightness. I suspect because of the very high battery drain and high heat it produces.
Auto Brightness is capable of increasing brightness to 2000 nits outdoors. I live in Florida and frequently visit the beach and do boating around the numerous waterways and the Gulf. I just turn on Auto Brightness when in those extremely bright conditions.
Auto Brightness can regulate the brightness so it reduces the brightness and hence internal temperatures to prevent the iPhone from shutting down. My wife like to manually set the brightness very high and when we’re out on hot days, her iPhone overheats and suffers from severe battery drain. Just our experiences.
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