Rockstar has annoucecd that there will be a launch day patch 1.03 for Red Dead Redemption 2 to fix bugs and other the problems in game at the last moment before launch. However, in order to not leak anything in the game, they haven’t give us a patch notes.
The size of this update will be 3.30 GB for PS4 and 3.2 GB for Xbox, if you are in japon the size will be a little bit smaller, and if you have preload the game, auto-update is recommanded to turn on.
Red Dead Redemption 2 will be available on October 26, 2018 for PlayStation 4 and Xbox One, pre-load has already started since its enormous file size. No PC version of Red Dead Redemption 2 has announced yet.