Lock by owner due to scam on iPhone

Can we assume you were tricked into logging into someone else’s account on YOUR device?

If so, please see: How to remove Activation Lock - Apple Support

NOTE: There is never a need to use someone else’s ID on your device. NEVER.

Take your phone along with the original receipt for it to an Apple store, they can unlock it for you.

Did you buy a used phone that still had someone else's Apple Account on it? If so, there's nothing you can do.

On the other hand, if someone has compromised your Apple ID, start here:

If you think your Apple Account has been compromised - Apple Support

Put your phone in lockdown mode

What did he say? I didn’t understand

He can't lock down the phone since someone else already blocked him from his phone. And lockdown mode wouldn't help anyway in this situation.

"What did he say? I didn’t understand"

Ignore the response from Techlover 14, you can't put your phone in lockdown mode if you can't get into it.