Any data from the Voxel World can be queried from gameplay code using the Query Voxel Layer and Multi Query Voxel Layer nodes. The two nodes do the same thing, but a multi-query queries multiple positions at the same time.

Query nodes output a struct containing the distance of the assigned volume layer (or height in the case of a height layer) at the given position. If Query Materials is enabled, the Material pin in that struct will contain a reference to the most prominent material at the query position. Metadata can also be queried by making an array with the relevant names plugged into the Metadatas to Query pin. They'll then be part of the Metadata map in the output struct.

The two Query Voxel Layer nodes, with the output struct broken out into its contents.