An HTC U12 render leak suggests that the phone will have a near bezeless display, which, if true would mean that HTC is finally following the trend that both Samsung and LG have already been implementing on their flagships since 2017, followed by numerous other brands from China and other regions. Though the leaked render doesn't quite accurately show where the edges of the display end in terms of bezels on the top and bottom of the phone, recent reports from back at the end of December of 2017 state that the U12 would be coming with some very thin bezels, and by the looks of this render it would seem that is very likely to be the case.
It's also been rumored that the HTC U12 would come with a 4K display, though it's also worth noting that some of Sony's phones have featured 4K display for the last couple of generations, but would only operate in 4K resolution when 4K content was being played, so it's possible that the U12 could come with a 4K display but work in very much the same way as Sony's 4K mobile devices. That said there is no indication that it would be one way or the other, so for the moment things are still just a rumor.
The leaked render does give off some detail about the phone's design, such as the placement of the volume up and down buttons and the power button, which are residing on the right side of the phone frame, similar to the Pixel and Pixel XL from 2016 but flipped so the volume buttons are placed above the power button. It's also possible to see the location of the charging port, which sits dead center in the bottom part of the phone frame just as on all of HTC's devices from last year, and while you can't see what type of charging port it is it's quite likely that it will be USB Type-C, as the U12 will be a flagship phone for HTC and it hasn't used anything but USB Type-C on its major devices for the past couple of years now. You can also make out one single front-facing camera, sitting to the right side of the phone's earpiece in the top bezel. So far this could be the best look at the upcoming U12, but more images could very well pop up before the phone's official announcement.