This might have been predictable, but the huge popularity of Call of Duty: Black Ops - Cold War has lead to the game's servers having a rough old time of it on launch day, with several players having trouble connecting to the game.
Players have been met with a message stating that "The Call of Duty: Black Ops Cold War server is not available at this time." Several players on Reddit have also complained of messages claiming wait times of up to "77000" minutes, or just over 53 days.
While it's unlikely players are going to be waiting that long, saturation on day one of an online game is inevitably a frustrating experience. The good news is, you should still be able to enjoy the single-player campaign mode, despite some claims to the contrary.
The queues will no doubt reduce over the next 24-48 hours, but in the meantime, there's plenty of other games to keep you occupied, including Assassin's Creed Valhalla, so it's not all bad I guess.