Will wrapping car battery with insulator help?

Modern fuel injection ,electronic ignition ,should start easily down to about 0 F (outside). So I would not bother with insulation. Insulation will slow cooling but overnight in wind it will cool to about the same temperature ;so, no real difference in battery temperature / voltage. Long ago ,with carburetor and points ignition, I took the battery out and kept it in a warm house overnight ( at 0 F). Next morning ,the battery slowly turned the engine but not enough to start. I see some cars have a little thermal insulation around the battery; That is to protect it from high underhood temperatures and ,hopefully extend life.

You have it backwards, battery insulators are used to protect batteries from excess engine heat rather than protect them from cold, as extreme heat is worse for batteries than cold. Car batteries have no heat source, so an insulating blanket is only going to slow heat loss, a car battery sitting overnight will still reach ambient air temperature.