How do I see my iPhone in bright sunlight?

To see your screen in bright sunlight, you'll need to change your screen brightness to maximum. To do this, swipe down from the top right corner on your iPhone to display the Control Center. Slide up in the box with the sun icon until it's completely white: 

You can also use anti-glare screen protectors like this one from Otterbox: https://www.apple.com/shop/product/HPQ82ZM/A/otterbox-amplify-glass-glare-guard