don't know apple id for this phone

Activation lock is a security protocol that can't be bypassed. Only the person it is locked to can unlock it.

If you bought this from someone and it came locked, try to get your money back, you will never be able to use the phone.

If your phone is Activation Locked - How to remove Activation Lock -

How to remove Activation Lock - Apple Support

The All Too Common SAD Reality of Buying a Used iPad/iPhone.

The All Too Common SAD Reality of Buying … - Apple Community

Mjbaggett wrote:

cant unlock iPhone 8 don't know passcode or  id

You’re here, asking this, which usually means the seller has disappeared and is unavailable to either release the lock or for a refund, which means this iPhone is forever a brick.

The All Too Common SAD Reality of Buying a used iPad/iPhone - Apple Community

To unlock the phone, you will need the Apple ID and Password of the person who originally set up the phone. Otherwise, the phone is useless.

If you purchased this phone, try to get your money back.