Sony remains one of the few smartphone manufacturers yet to adopt the new 18:9 display ratio. The company is known for its "boxy" form factor and LCD panels in a world where most OEMs are adopting AMOLED displays and curvier forms. Word a few months ago claimed that 2018 Sony flagships would offer a new design experience, though, and we may have one of those on our hands soon. An Xperia device has stopped by at FCC for certification, and listed details point towards what appears to be an 18:9 display.
18:9 is the current trend. The ratio allows for larger displays within a constant body size. For instance, a 6-inch 18:9 smartphone feels quite similar to a standard 5.5-inch 16:9 one. The ratio basically elongates the display's height, while keeping the width constant.
According to the FCC listing, this new Xperia device features a 5-inch display, with a length of 135.43 mm, and a height of 64.63 mm. In juxtaposition, the Xperia XZ1 Compact features a 4.6-inch display, with a height of 129 mm, and a width of 64mm. The fact that the width is mostly the same while the height increases is an indication of an 18:9 display, as the width would have seen a larger bump in size if it were a 16:9 display.
Nothing else is known about this device, but there's a chance it could be the Xperia XZ2 Compact, the successor to the only true compact flagship released in 2017. The XZ1 Compact was released towards the end of the year, in August, though, so this could be too early for a sighting.