I’m sorry to hear about your situation. If the iPhone you purchased is Activation Locked, it means the previous owner didn’t sign out of their iCloud account, which is needed to erase the device and remove it from their account.
You have a two options:
1. Contact the Seller: The simplest solution would be to contact the seller and ask them to remove the Activation Lock. They need to sign in to their iCloud account on the Apple ID website, select the device under their list of devices, and remove it. This can be done remotely, they don’t need physical access to the iPhone.
2. Return the Phone: If the seller is not cooperative or you can’t get in touch with them, you should try to return the phone. eBay has policies in place to protect buyers from this kind of situation. File a claim with eBay’s Money Back Guarantee program.
Activation Lock is a security feature and there’s no bypass that Apple officially supports. It’s intended to deter theft by making it difficult for people other than the owner to use the device. Always check the status of the device before buying it second-hand in the future.
I hope this information helps, and I’m sorry that you’re going through this situation.