XR is bound to the HUD’s resolution, but you can achieve the same effect as hardware scaling if you define the framebuffer scaling when initializing your session. These are the default values - Babylon.js/webXRManagedOutputCanvas.ts at master · BabylonJS/Babylon.js · GitHub
You can use it this way - https://www.babylonjs-playground.com/#5EQA9Y#3