Have you tried turning it off and then on again?

You shouldn’t have to turn off your iPhone very often. If you’re not going to use it for a few hours, it’s not worth the hassle (and minuscule battery life savings) to shut it down.

But, if you know you’re not going to use your phone for a couple days, or on a very long international flight, and you want to save every last ounce of battery life, shutting it down can be an effective option.
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Read full post here:
https://www.macworld.com/article/3237747/how-to-power-off-your-iphone-11-11-pro-x-xs-xr.html