[UPDATE] We've reached out to CD Projekt RED and they have provided the following statement.

　　Yes, the game has just received an upgrade patch, enabling it to take advantage of the additional power offered by the PS4 Pro. When playing the game on a PS4 Pro system, The Witcher 3: Wild Hunt and all its additional content feature support for 4K resolution and a slight boost to performance.

　　[ORIGINAL STORY] A new update has been released on PlayStation 4 for The Witcher 3, the latest entry in the series developed by CD Projekt Red now out on Xbox One and PC as well.

　　The new update, version 1.51, has been released a few minutes ago. According to reports, the update is around 140 MB big, and it includes the PlayStation 4 Pro support that had been announced not too long ago. As the reports have yet to be confirmed, we must take them with a grain of salt until an official confirmation comes in.

　　The Witcher 3 is also going to get Xbox One X support before the end of the year, as revealed last month by CDPR president Adam Kicinski, who also talked about an imminent release of the game's PlayStation 4 Pro update.

　　We’ve prepared a 4K version which will be available on PlayStation Pro in just a few days and by the end of the year, it will be available on Xbox One X.

　　The Witcher 3 is now out on PC, PlayStation 4 and Xbox One. We will keep you updated on both PS4 Pro and Xbox One X patches as soon as possible, so stay tuned for all the latest news.