Default Materials
TerrainTexturePacksJson2 FString {"asphalt_side":7551990829,"asphalt_top":7551987784,"basalt":7551978967,"brick":7547633775,"cobblestone_side":7547650812,"cobblestone_top":7551995071,"concrete_side":7547630026,"concrete_top":7547337977,"crackedlava":7551983669,"glacier_bottom":7551949364,"glacier_side":7551944502,"glacier_top":7551935562,"grass_bottom":7551928998,"grass_side":7547623564,"grass_top":7547336797,"ground":7547349135,"ice_side":7547659308,"ice_top":7547655101,"leafygrass_side":7546666342,"leafygrass_top":7546664715,"limestone_side":7547676869,"limestone_top":7547673056,"mud":7552025321,"pavement_side":7547684004,"pavement_top":7547679257,"rock":7547645700,"salt_side":7547669153,"salt_top":7547663777,"sand_side":7546659291,"sand_top":7547636223,"sandstone_bottom":7552020001,"sandstone_side":7551965250,"sandstone_top":7551956653,"slate":7547627210,"snow":7551952124,"woodplanks":7547642685}
2022 Materials
TerrainTexturePacksJson2022 FString {"asphalt_top":9438410491,"asphalt_side":9438410904,"basalt":9438413227,"brick":9438453826,"cobblestone":9438459300,"concrete":9483105529,"crackedlava":9438582231,"glacier_top":9438851661,"glacier_side":9438853821,"glacier_bottom":9438867942,"grass_top":9438956437,"grass_side":9439010785,"grass_bottom":9439012675,"ground":9439044431,"ice_top":9483105883,"ice_side":9439080020,"leafygrass_top":9439150097,"leafygrass_side":9439152680,"leafygrass_bottom":9439264706,"limestone_top":9439416055,"limestone_side":9439426299,"mud":9439517016,"pavement_top":9439519914,"pavement_side":9439527816,"rock":9439546316,"salt_top":9439566986,"salt_side":9439576187,"sand_top":9439585561,"sand_side":9439594457,"sandstone_top":9439596892,"sandstone_side":9439605693,"slate_top":9483106252,"slate_side":9439622374,"slate_bottom":9439631253,"snow_top":9439632387,"snow_side":9439640395,"woodplanks":9439658515}
They are uploaded under asset type TexturePack so I’m not sure how thats all handled.