Shutdown

Curlygirl ~ Shutting down unexpectedly can be a symptom of a battery in need of replacement:

"...The power management system determines the capability of the battery to supply this power, and manages the loads in order to maintain operations. When the operations can no longer be supported with the full capabilities of the power management system, the system will perform a shutdown to preserve these electronic components. While this shutdown is intentional from the device perspective, it may be unexpected by the user." [Source: Apple]

…So, if the battery of your iPhone is the original one, it may need replacement. What's the Maximum Capacity % here?...

Settings > Battery > Battery Health

iPhone Battery & Power Repair

About genuine iPhone batteries

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

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Curlygirl123 wrote: "...It is 83%"

That's about the % to be expected from an iPhone 8+ with its original battery. Replacing the battery is almost certain to solve the shutdowns:

iPhone Battery & Power Repair

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Curlygirl123 wrote: "I am not familiar with technical jargon."

Okay, on your iPhone, tap this icon which is the Settings app:

...Then scroll down to Battery and tap it. Then tap Battery Health and tell us what the Maximum Capacity % is.

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Hello,

You might try cleaning the charging port:

How to clean your iPhone's charging port

Good luck.

Curlygirl123 wrote: "it charges up to 100%"

That's not what I asked. Again, what's the Maximum Capacity % here?...

Settings > Battery > Battery Health

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