I bought a second hand Iphone 14 that seems locked for icloud and/or apple ID

If you have bought 2nd hand iPhone, you must contact the seller (hopefully it is the previous owner), otherwise you have been scammed.

Each Apple device is linked/associated with an Apple ID of the person who did the setup.

Activation Lock prevents anyone who is not the owner from using this iPhone.

To unlock the Phone, you need the Apple ID and password of the previous owner, that were used during set up.

So you have to contact the previous owner.

The previous owner has to read -> this Apple article: What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch -> What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

Then the previous owner has to remove the iPhone from his account, see this Apple article:

Check your Apple ID device list to see where you're signed in

Check your Apple ID device list to find where you're signed in - Apple Support

Then you can sign in with your own Apple ID.

See the following Apple articles:

Activation Lock for iPhone, iPad, and iPod touch

Activation Lock for iPhone, iPad, and iPod touch - Apple Support

How to remove Activation Lock -> How to remove Activation Lock – Apple Support (UK)

• If you need help removing Activation Lock and have proof of purchase documentation, you can start an Activation Lock support request.

Read this before you buy a newer iPhone.

You can also contact Apple support for help, -> Get Support (apple.com)

You have to show proof of ownership of your product, provide all documentation showing your purchase of the device.

If you do not have additional proof of ownership, contact the reseller. They may be able to provide the original purchase document.

Once Apple receive your proof of ownership, Apple will further review your request and provide an update.

See also -> Keep your receipt after you buy an Apple device

Keep your receipt after you buy an Apple device – Apple Support (UK)

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Ask your money back if possible, perhaps you have bought a stolen iPhone.

If you can't get in touch with the seller 'that guy', you can't use the iPhone.

Having read everything what you have written, plus it being blacklisted suggests strongly it was stolen. If you want to, you can read all the links provided in a previous post about the activation lock feature, but in short, there is nothing you can do other than recycle the device. There is nothing Apple or any service store can/will do to find the owner or remove the lock since apparently you do not have a true receipt from an official Apple vendor. If a device is stolen, the owner has the option to mark it as lost in their account and it to leave a message that will display, but apparently this has not been done.

If you try to buy a used iPhone in the future, you can get them from Apple. If you try a private party, make sure they have done all the things in this support article (don't just take their word they have done this) What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

In this case, it seems to be difficult to find the real owner. Just take it to a police station.

You can't use the iPhone.