Head size does not correspond to intelligence, but brain size, shape, and composition does. Aside from a few exceptions, animals with larger brains do tend to have more intelligence.

Does big forehead mean intelligence?

A broad forehead

According to the practice of Chinese face reading, having a broad forehead is a sign of intelligence and skill. Generally, they are also believed to be able to finish tasks earlier and usually don't need things explained to them.

Does a larger head mean a larger brain?

Even though head size also depends on factors such as the muscularity of the head and thickness of the bone, it's very likely that a bigger head means a bigger brain.