Update my iPhone

If you have an iPhone 8, which is still on iOS 14, you have skipped a couple years worth of updates. You'll find better success using a computer to do the update, which can be updated to iOS 16.7.7. It cannot be updated to the current iOS 17.4.1

Here is a link which explains how to use your computer to update your iPhone --> Update your iPhone, iPad, or iPod touch with iTunes - Apple Support