my iphone 8 stucks at 80% while charging. How to fix this?

Hello julianne222.
Welcome to Apple Support Communities.
If I'm understanding correctly, your iPhone will not charge past 80%. I will be glad to assist you with this.
Take a look at the information below to see if it helps, from our article: If your iPhone, iPad, or iPod touch won't charge

If your device stopped charging at 80 percent

Your iPhone might get slightly warmer while it charges. To extend the lifespan of your battery, if the battery gets too warm, software might limit charging above 80 percent. Your iPhone will charge again when the temperature drops. Try moving your iPhone and charger to a cooler location.

Cheers.