Question SpatialMappingWireframe - how to obtain

Hello, I recently started a project and was messing around with the skybox settings when I selected the "SpatialMappingWireframe" as my skybox, and it looked super right for my project. However, when i updated to the newest version that came out I lost the ability to use that as a skybox, and when selected shows the pink missing textures material. Is there any way around this, or any way to just download the texture outright? I tried going in through terminal but the unity_builtin_extra is not a openable folder.