My lo is close to 9 weeks old and his hair is kinda fine type. How to make baby hair grow denser?

The mommies in my family swear by the wonders of olive oil (for hair, not cooking haha). They would take a tiny drop and massage it into baby's damp hair and scalp after bathing. I, myself, benefited from this method. I did not have hair till I was nearly 2 years and after my late grandmother tried this method, it worked and now my hair is crazy thick and despite all the dyeing and harsh chemical treatments over the years, it is still rather healthy and strong.