iCloud
I have buy old iPhone 8 but this phone is totally clean but this phone iCloud is locked so what is the process iCloud unlocked
iPhone 8
You will need the assistance of the previous owner.
See the following instructions: Activation Lock for iPhone, iPad, and iPod touch - Apple Support
If the previous owner will not assist, the phone is useless. If you purchased through a 3rd party (e.g., try eBay) try to get a refund.