How can I recover a stolen or lost iPhone 15 pro max purchased from eBay?

Sorry, but the chances are you've been scammed if the seller refuses to help you. Apple won't help you because you are NOT the original buyer and you don't have the original purchase receipt from when the phone was originally purchased. If eBay won't help you, I'd dispute the charge with your credit card company, but they may defer to eBay on this. This has absolutely nothing to do with Apple. Buying used devices like iPhones on eBay is a bad idea, which often has a bad outcome.

You are likely going to have to recycle the phone responsibly and learn from this unfortunate buying decision. Read this --> The All Too Common SAD Reality of Buying … - Apple Community

Often deals which appear to be really good are in fact really bad. If you want to buy a used iPhone, Apple has a Refurbished Store and phones purchased there are like new and come with a one year warranty from Apple directly.

Here's a link --> Certified Refurbished Products - Apple

Lesson learned. It is unfortunate the eBay will not protect your purchase. The iPhone still belongs to the person that lost it and are also able to track the device to know where it is at and a purchase on eBay will certainly not transfer ownership. Your only option was to get a refund from the seller with possible help from eBay, but since that is not possible, recycling is your only option. There is nothing Apple can do about it.

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

No.

If eBay denied the claim under their buyer protection program, that's the end of it.

Toss it in the recycle bin at your local electronics store.

Apple won't get involved.

Nope.

Phone is useless to you, Apple won’t help you at all since you aren’t the legitimate owner.