It looks like the end of the console-exclusive era is marching ever forward. On the one hand, more game studios are embracing simultaneous launch strategies, as was recently emphasized by both Square Enix and Ubisoft adopting multi-platform simultaneous launches for Fantasian Neo Dimension and Assas...
I believe for the first Outer Worlds it was multiplatform because it was published by Private Division (owned by 2K at the time), not Microsoft. Obsidian wasn’t owned by Microsoft yet when the game was being developed. Of course, it just makes businesses sense to release the sequel on PS5 too for more money from sales.