Depends on what headset you are using.
The game itself does not support OpenXR, but there are wrappers that redirect OpenVR (SteamVR) calls to OpenXR instead, which can bypass SteamVR as a middle man, if your headset is more "native" to a different OpenXR compliant VR runtime than Valve's.
I use a Valve Index, so I'm already "close to the metal" so to speak. :7
I have not kept up, but latest I knew of, what you are looking for is:
https://github.com/aashishvasu/OpenComposite
That will do the redirecting I mentioned. From that point, you can choose whichever OpenXR compliant runtime you want to use; And additionally maybe stick OpenXRToolkit (EDIT:
https://mbucchia.github.io/OpenXR-Toolkit/ ) between the game and the runtime, in order to try to force some degree of foveated rendering, or other manipulation.
If you stay with OpenVR, have a VariableRateShading-capable graphics card (RTX20x0 and up), and wish to try foveation, check back at fholgers github page where you got openvr_fsr, and give VRPerfkit a try, as an option -- it will allow you to render less detail in the periphery (radius of full detail configurable), for a percent or two of workload relief...