Hello, this is Mark! I bought this phone from a third party on OfferUp. Thought it was unlocked to any carrier but it's locked to iCloud. I was wondering is it a way you can help me unlock it or get in contact with the previous owner..!??

Sorry, but we have no way to know who the previous owner might be.

Unfortunately, the phone is going to be useless unless you can contact the original owner to get his Apple ID and Apple ID Password.

Return for refund is likely going to be your best bet.

Sadly, you have been scammed and there is no way you can ever unlock this iPhone with the original credentials used to set up the phone. Offer, Facebook, eBay, etc., are the absolute worst placed one can buy a used iPhone. It's where thieves go to unload stolen phones, then disappear. If you can't reach the seller, who is most likely the original owner of the phone, you're the proud owner of a useless iPhone you can never use. If you can't get your money back (you likely can't), then recycle the phone responsibly and chalk this up to a bad buying decision. Apple will NOT help you and no one here can either. The phone is useless to you.

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

187papí wrote:

How can I contact them if I don't have a number or anything on them!?

You simply can't. You've been scammed. Game over. Accept your money bought a useless iPhone you can NEVER use. Sorry. Did you read the link I provided? No one can help you here. If you want to buy a used iPhone, buy it from the Apple Refurbished Store. Buying from someone you don't know is pretty much a guarantee for disappointment.

The phone is useless unless you know the Apple ID and Password of the person who set up the phone previously.

Sorry but you got scammed.

Drop the phone off at the recycling place.

You don’t and no one is going to give you that information.