When creating a model with about 3.5 million meshes and running it with EE12 version, it shows an insufficient virtual memory error.
There are no limits in the software for the size of the grid. The issue you are facing is related to your hardware. If you increase the RAM on your machine sufficiently, it can theoretically handle a model of this size. We recently tested a machine with 64 GB RAM, and it can run a model with 540,000 horizontal cells.