Class PortalBlock

src/main/java/com/example/tutorialv3/blocks/PortalBlock.java:20–54

import net.minecraft.world.phys.shapes.VoxelShape;

public class PortalBlock extends Block {

    // Our block is lower then a normal block. That causes the player to sink in it when he stands on the block
    // And that in turn causes our 'entityInside' test to detect the player
    private static final VoxelShape SHAPE = Shapes.box(0, 0, 0, 1, .8, 1);

    public PortalBlock() {
        super(Properties.of(Material.METAL)
                .sound(SoundType.METAL)
                .strength(-1.0F, 3600000.0F)
                .noDrops());
    }

    @Override
    public VoxelShape getShape(BlockState state, BlockGetter level, BlockPos pos, CollisionContext context) {
        return SHAPE;
    }

    // This works because our block isn't a full block
    @Override
    public void entityInside(BlockState state, Level level, BlockPos pos, Entity entity) {
        if (entity instanceof ServerPlayer player) {
            if (level.dimension().equals(Dimensions.MYSTERIOUS)) {
                teleportTo(player, pos.north(), Level.OVERWORLD);
            } else {
                teleportTo(player, pos.north(), Dimensions.MYSTERIOUS);
            }
        }
    }

    private void teleportTo(ServerPlayer player, BlockPos pos, ResourceKey<Level> id) {
        ServerLevel world = player.getServer().getLevel(id);
        Tools.teleport(player, world, new BlockPos(pos.getX(), pos.getY(), pos.getZ()), true);
    }
}