Tap on the top of the screen to have the iPhone scroll to the top of the current page.
If you have an iPhone 14, you can tap on either side of the Dynamic Island and the phone will instantly scroll up.
With an iPhone X or any of the models with the notch, you can tap on either side of the notch.
If you have an older iPhone without the Dynamic Island or a notch, you can achieve the same thing by tapping the clock on the status bar.
The iPhone holds a lot of secret functionality that can be unlocked with simple gestures or taps. Make sure to check out how to use gestures to copy and paste text between your iPhone or iPad. Or read up about how to quickly copy text from iPhone photos using its Live Text feature.