RoundTreesPack/input/assets/regions_unexplored/blockstates/brimwood_log_magma.json

{
  "variants": {
    "transition_block=true": {
      "model": "regions_unexplored:block/brimwood_log_transition"
    },
    "transition_block=false": {
      "model": "regions_unexplored:block/brimwood_log_magma"
    }
  }
}