A curious question from someone exploring Islam

Assalamu alaikum, everyone. I hope it's okay to ask something here. I’m not Muslim, but I’ve been exploring a bit about Islam lately. Growing up in the US, I didn’t really connect with my Middle Eastern roots-honestly, it felt kind of embarrassing because of how things are here. But a while back, when I was going through a rough patch, I stumbled upon a book called The City of Brass, and I ended up loving the whole trilogy. It made me genuinely proud of where I come from, and I’m so grateful to the author, S.A. Chakraborty, for that. Now, though, I’m a little confused. She’s mentioned in interviews that she converted to Islam as a teenager. But I noticed she doesn’t cover her hair, and from my very limited knowledge, I thought that was required for Muslim women. So I’m wondering, can a woman truly practice Islam without wearing a hijab? I’m really just trying to understand, and I know I have a lot to learn. Jazakallah khair for any insights.