Assuming you are referring to an iPhone X that was purchased through Amazon's Renewed or Refurbished program:
According to Amazon, all Renewed products are tested and certified by qualified suppliers to work and look like new, and come with a minimum 90-day supplier warranty. Products on Amazon Renewed are also backed by Amazon's return policy.
Similarly, all Refurbished products on Amazon are certified to work and look like new, and come with the same minimum 90-day warranty as Renewed products.
So in short, Amazon Renewed and Refurbished products should work just like a new product, but may have some cosmetic blemishes. These products come with a minimum 90-day warranty, and are backed by Amazon's return policy.
