Custom Map Model?

So, i know how to create a custom “block” with some kind of block (e.g. mob spawner) and a model pulled to cover it.
I just know it’s okay with small builds, but with more major ones? It’ll gonna hate every single bit of me.
I just wondered if there’s any way to create some kind of map model in Minecraft? Perhaps some kind of Blockbench plugin?
I guess making interactables a different model is fine, they dont appear that much, but… normal blocks? In a PART of a map there’s at least a 100… so that’s at least a 1 entity per block, which will just eat my whole as- CPU alive. So.
Does anyone has some kind of solution to this, or do i just re-texture blocks Minecraft already has?