According to the official Metal Gear Twitter, they've released a PlayStation 4 Pro patch that takes advantage of the extra horsepower behind the PS4 Pro. It has gone live today and according to Konami, it offers "enhanced performance".
Official patch notes are pretty minimal aside from a short description of the upgraded console itself. However, the Tweet offers a bit more insight on the update.
Even if you have a 1080p screen, you’ll enjoy the improved #MGSVTPP performance thanks to today’s patch.
— METAL GEAR OFFICIAL (@metalgear_en) October 31, 2017
As stated above, the PS4 Pro patch increases the game's resolution to 4k, as well as improving framerates. Those with a PS4 Pro but not a 4k screen can also benefit from the increased framerate. Those with Metal Gear Solid V: The Definitive Experience, which comes with MGS V: Ground Zeroes, will also benefit from the performance improvements in the prequel.
Metal Gear Solid V: The Phantom Pain is currently free for PS Plus subscribers. It will also be available for Xbox owners through the Xbox Game Pass in November, but there's no word on whether or not the Xbox One X will bring a "Pro" version of the game.