You’ve been able to use one physical SIM and one eSIM on your iPhone for dual SIM capability since eSIM became a reality and Apple accepted the standard on its iPhones.
However, starting with the models released today, you have another option for achieving the same result. Not only do the iPhone 13, iPhone 13 mini, iPhone 13 Pro, and iPhone 13 Pro Max offer dual SIM through physical SIM + eSIM, but they also include dual eSIM functionality, which means you may use two eSIMs instead of a physical card on your brand new iPhone.
It’s worth noting that Apple’s documentation makes no mention of adding a physical SIM to the mix to make it a triple SIM situation, so don’t hold your breath. It’s still a dual SIM situation; the only difference is that you now have two ways to get there.