Settings
iPad 8th generation and iPhone 8plus exsperimental WebKit features be set at
iPhone 8 Plus, iOS 14
The “experimental webkit settings” page is perhaps poorly named - as this page includes advanced settings that influence many key configuration items.
Unless you know exactly what you are doing, you would be well advised to leave these settings well alone. Short of a full reset of all iPad Settings, there is no “undo” or settings button that can restore the default Webkit settings.