Can you buy crypto on a dex?

Excuse me, I'm curious about something. I've been hearing a lot about decentralized exchanges, or DEXes, lately and I'm wondering if it's possible to buy cryptocurrency on one of these platforms? I've used centralized exchanges before, but I'm interested in exploring the decentralized option. Could you please elaborate on whether or not it's possible to purchase crypto on a DEX, and if so, how the process differs from using a traditional centralized exchange? Thank you in advance for your help.