Jailbreaking an iPhone 8 can be done using various tools such as Checkra1n, unc0ver, and others. Here is a step-by-step guide to jailbreak your iPhone 8 using Checkra1n:

1. Download the Checkra1n jailbreak tool on your computer.
2. Connect your iPhone 8 to your computer using a USB cable.
3. Open the Checkra1n app on your computer.
4. Click "OK" in the pop-up warning window.
5. Click the "Next" button.
6. Follow the on-screen instructions to get your iPhone into DFU mode.
7. The app will start to jailbreak your iPhone.
8. Click "Done" after the process is successful.

Please note that jailbreaking an iPhone can void its warranty and may cause security issues. It is important to proceed with caution and at your own risk.