Answer is Yes. I’ve bought both iPhone 6S Plus and 7 Plus from Amazon and they are working great without any defect.
Do ensure that the iPhone you are purchasing is fulfilled by Amazon and covered by Amazon Prime. I think you are good to go then. Once you receive the iPhone, set it up and check its serial number in Apple’s website. The warranty period should start from the day you put your SIM card in the iPhone. In case of any issues (very rare chance) get back to Amazon or Apple help. Any such concern should get sorted.
Hope this information is useful…
