Multiplayer Update
From Kerbal Space Program Wiki
The Multiplayer Update is the 5th of 5 currently planned major updates for KSP2 Early Access.
Features
The Multiplayer Update will add the ability to join a multi-player server and play with friends, either cooperatively or as a space race. 4 space agencies, each with their own space center, will exist on Kerbin. Space agencies can compete against each other, or cooperate by sharing resources.
Multiplayer was originally a planned feature for KSP that has now been moved to KSP2.
Release Date
Currently the release date is unknown, but will likely be in more than a few months (as of 1/4/24).