How do I unlock my Activation Locked iPhone 8?

If it is asking for your Apple ID and Apple ID password, enter them.

If you are the original purchaser of this phone, and have proof of purchase documentation from Apple or an Apple Authorized Reseller, clearly showing your name, and the phone's serial number, you could file an Activation Lock support request.

How to remove Activation Lock - Apple Support

If this is a second-hand phone, and you are now discovering that it is Activation-Locked to someone else, see:

The All Too Common SAD Reality of Buying a Used iPad/iPhone – Apple Community

You can't unlock it without the Apple Account username and password that was registered to the device before it was erased. If you purchased this pre-owned, consider contacting the seller.

Please define unlock.

Carrier lock?

Passcode lock?

Activation lock?

The hosts renamed the post. We don't actually know what the OP meant by "unlock".

The OP did not specify that it was activation locked.

Locked to owner means activation lock.