https://wccftech.com/red-dead-online-details-beta-november/

Red Dead Online, the multiplayer component of Red Dead Redemption 2, won’t launch alongside the game. Instead, it will initially release as a beta in November, accessible to everyone who purchased Red Dead Redemption 2.

This isn’t a surprise, as Rockstar Games did the very same with Grand Theft Auto V. The developer also shared a brief statement on the official blog: