[1.16.5]How do i get bounding box of block model?

I'm trying to make entity that has model of block and has size of block. I was able to make it rendered with model of block, but i cannot get bounding box of block model.
I tried getting quads of model, and getting minimal/maximum int values from its vertex datas that is int array, but i have trouble getting quads from block model

BlockRendererDispatcher blockrendererdispatcher = Minecraft.getInstance().getBlockRendererDispatcher();
List<BakedQuad> quads = blockrendererdispatcher.getModelForState(block).getQuads(block, null, new Random(), EmptyModelData.INSTANCE);

The List<BakedQuad> is empty after this operation. passing non-null direction instead of null while using getQuads method make it return non-empty list, but doesn't it make it only return quads of the specific side?
Also, i'm not sure i'm doing this right the way, "entity that has size of block", means entity that has minimal size required to wrap unrotated model of block