Larian Studios has released Patch 5 for Baldur's Gate 3, and it's rather large.
The update clocks in at roughly 30GB and requires approximately 130GB of free space to install.
If it comes to pass that you do not have enough space to install the update, Larian suggests uninstalling Baldur's Gate 3 and re-downloading the patched version.
Patch 5 contains a playable epilogue which finds you joining a get-together organized by Withers at camp six months after the final events of the game. Here, you will say your "final goodbyes" to your party.
The epilogue features 3,589 lines and two new game modes. These modes are Custom Mode and Honour Mode, the first of which allows you to hide things so the game has more of a realistic D&D feel to it.
Other options in Custom Mode include Short Rests fully healing the party, as well as disabling Death Saving Throws, or even the ability to hide failed Perception Checks, which means you’ll never know there was even a roll to begin with.
Honour Mode ups the difficulty and features a Legendary Action system which changes enemy actions during battle. Inspiration points will also become more valuable, as loading previous games - or ‘save scumming’ - is disabled, so you will need to keep count. Some of the more powerful unintended exploits have been removed should you embark on an Honour Mode adventure, though have been kept open to exploit in other difficulty settings. When you die, you will be presented with statistics of your journey, including how long you survived and how far you made it. Should you choose, you can continue your adventure, which will then disable Honour Mode. If you manage to complete the entire game with Honour Mode enabled - and without dying - you will be awarded the coveted Golden D20.
Patch 5 also includes improved inventory access, allowing you to manage the inventory of all companions from one single UI, regardless of whether they’re currently in the active party. It also brings performance improvements engineered as a consequence of the Xbox version of Baldur’s Gate 3, which benefits all platforms. It includes many tweaks, fixes, and additions.
You can look over the full patch notes on the official website - just beware of spoilers.