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Trying to use my phone in bright sunshine.
turned everything off in settings to stop phone from dimming.
searched online for anything I have missed.
still dimming on its own. Downloaded latest update and is still dimming.
VERY annoying.
iPhone X, iOS 12
Have you enabled Low Power mode?
To turn Low Power Mode on or off, go to Settings > Battery. You can also turn Low Power Mode on and off from Control Center. Go to Settings > Control Center > Customize Controls, then select Low Power Mode to add it to Control Center.
When Low Power Mode is on, your iPhone will last longer before you need to charge it, but some features might take longer to update or complete. Also, some tasks might not work until you turn off Low Power Mode, or until you charge your iPhone to 80% or higher.
Low Power Mode reduces or affects these features:
When Low Power Mode is on, the battery in the status bar will be yellow. You'll see 
and the battery percentage. After you charge your iPhone to 80% or higher, Low Power Mode automatically turns off.
Low Power Mode is available only on iPhone.
Use Low Power Mode to save battery life on your iPhone - Apple ...
Have you enabled Low Power mode?
To turn Low Power Mode on or off, go to Settings > Battery. You can also turn Low Power Mode on and off from Control Center. Go to Settings > Control Center > Customize Controls, then select Low Power Mode to add it to Control Center.
When Low Power Mode is on, your iPhone will last longer before you need to charge it, but some features might take longer to update or complete. Also, some tasks might not work until you turn off Low Power Mode, or until you charge your iPhone to 80% or higher.
Low Power Mode reduces or affects these features:
When Low Power Mode is on, the battery in the status bar will be yellow. You'll see and the battery percentage. After you charge your iPhone to 80% or higher, Low Power Mode automatically turns off.
Low Power Mode is available only on iPhone.
Use Low Power Mode to save battery life on your iPhone - Apple ...
iPhone X randomly dimming
