What would be the best way to recreate the block breaking system from Battle City?

I'm trying to recreate Battle City and I'm not sure about the best way to destroy the blocks part by part as they get shot.

The grid in the actual game is 16x16 (as I've configured in my project) and a single brick block is divided by smaller pieces of 4x4 (which I have not done yet) as it requires 4 projectiles to break the entire brick block.

How would be the best way to accomplish that? Is there a way to divide a grid block into smaller parts? Or would it be better if I set the whole grid to 4x4, instead of 16x16?