So you need a couple of things (most mentioned above, but you need all of them):
- A Ray Tracing Capable GPU, like an NVIDIA RTX card or latest gen AMD
- In plugins, enable the GPU Lightmass plugin
- In project settings, set RHI to DX12
- In project settings, Enable Virtual Texture Support and Enable Virtual Texture Lightmaps (to show progress bars and enable ‘bake-what-you-see’ baking)
- In project settings, Enable Ray Tracing
- Restart the engine
Oh, and don’t forget to switch on “Use Irradiance Caching” for inside scenes for the best results