Place the phone in my front jacket (chest) inside pocket earlier this evening and it comfortably fits! The phone is so slim and small compared to the Plus model. I know it is narrower, and perhaps a hair thicker...but overall the footprint is greatly reduced. My 6s Plus on the other hand, could only be crammed into the pocket and then it looks like I'm wearing a singlet-breastplate! Like a huge rectangular platter on my chest. LOL.
I spent at least an hour with my 6S Plus and my new X side by side with the screens displaying the same content - emails, web pages, different app screens (Music, YouTube, Netflix, News, NYT, various settings options) and the only screen reduction that impacts viewing/use is the slightly narrower screen. The useable screen height on the X is larger than I expected...and apps which are optimized for the X have more vertical space than the Plus model screens. So, what can I do?
Marvel at the beauty, saturation, and total appearance of the OLED vs the LED. Having these two side by side on the same pages/apps, the LED screen reminded me of looking at a CRT screen when flat screens first became popular! I only really noticed the additional light and thickness of the glass on the LED when comparing it to the OLED. It is almost like looking at a beautifully printed/published page (on high quality paper!).