This guide will show you how to install an iOS Beta Profile on your device.
Beta Download Center - AppleBetas.tk
First, visit the Apple Betas beta download center.
Scroll until you find the iOS Beta Profile section and click the blue Download button.
Now a prompt will appear, click iPhone if the iOS Beta Software Profile is selected. If you want the watchOS Beta Software, download that instead.
Tap Install in the Settings app, then enter your passcode to continue.
Agree to the iOS Beta message from Apple so the process can be completed.
Now restart your device and check for updates! You should now see the beta software available for download.