https://arstechnica.com/gadgets/2017/11/youre-gonna-need-a-case-iphone-x-fares-poorly-in-first-drop-tests/

As we suspected in our review, the iPhone X is not faring well in the first drop and durability tests. Two different drop tests showed immediate damage to the device.

Consumer electronics site CNET ran a drop test from a height of three feet. The glass at the corner of the phone cracked on the very first test, which dropped the phone on its side. A second test dropped the phone on its face, leading to even more fractures. CNET concluded that dropping the phone without a case is "out of the question."