The house immediately south of my property was just torn down and a new house is being built. The new house is at least 3 or 4 times the size of the old property and the layout of the house on the lot will be configured in a way that will completely block all the light to my windows and completely block the one patch of sunlight that I get in my driveway/patio. What can I do?

Probably not much. While there is such a thing as an easement for view, light, air, or other similar restrictions on neighboring properties, it’s unlikely that your neighbor will grant you such an easement at this point. I’m assuming you don’t already have one (they’re very unusual, in any case).

Most people rely on the local zoning and building ordinances to maintain some reasonable restriction on construction on neighboring properties. Again, I’m assuming that your neighbor has all the required permits for construction, so is either not violating those rules or obtained the appropriate variances (without your complaints at the time).

You could try talking to your neighbor to see if there’s any flexibility in the plans, but again, at this stage it’s probably too late. The time to have this discussion would have been the design phase, not after construction has started.