While fixing a few minor issues.
Square Enix released yesterday a sixth patch for the Microsoft Windows PC version of Rise of the Tomb Raider on Steam. That patch brings that game up to version 1.0.647.2.
Aside from a few gameplay and big fixes which is fully detailed here, that patch improves stereoscopic 3D rendering.
That patch doesn't fix the Steam overlay crash that some users have been experiencing. Valve is still investigating that issue.
Assuming you're using the default settings in Steam, that patch will be downloaded and installed automatically after you load that client.