I bought an iPhone that is locked to owner,Is there a reward for finding it ?

No, but there is a loss. Apple cannot unlock a locked device, you will have to contact the seller. That is the saying, buyer beware, by buying a used device from someone, you are assuming the risks that it can be activation locked and practically useless if it is.

Refer to this article for more information: The All Too Common SAD Reality of Buying … - Apple Community

Whether or not there is any monetary reward, the real reward is being able to look at yourself in the mirror.

If the phone is locked to the person from whom you bought it, and they just failed to prepare it properly for resale, you could take it back to them and ask them to complete these steps, then return the phone to you.

What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

If it is locked to someone else, there is a good chance that the phone is stolen. Do you want to be in possession of stolen property?

dcypbs wrote:

I recently bought an iPhone that is locked. Is there a reward for finding it ?

No.

Return a lost, locked iPhone - and you see message that says reported lost or stolen,

Return a lost, locked iPhone - Apple Support

No reward, but you do have a personal tracking device monitoring your every move. The owner is still able to track it, so they know exactly where it is.

Yes, the reward is being an unselfish hero, returning the iPhone to its owner. 😉

The reward is making someone smile again! 😇

Many of us here answering your question are not getting paid.

We answer your question because helping you is our reward. 🎖️

Thank you! 👋🏼😉