A VDB is just another primitive in Houdini, which also happens to have its own transform (eg. like sphere primitives). So you can just scale it using the Primitive SOP. All this is does adjusts the transform that gets used by the VDB.
Depending on the fields you're trying to render, you may need to multiply the fields (each voxel's value needs to multiplied as well) themselves up by 100 as well the transform, say velocity or an sdf for instance, you can use a volume vop and just multiply all the fields by 100.
