Apple asserts that its new iPhone 13 series is an upgrade on the previous line-up in a number of ways. However, charging speeds and accessory compatibility were not among them. A Twitter user claims to have tested all 4 new iPhones out with 20W and 30W USB-Power Delivery 2.0 (USB-PD 2.0) bricks, and asserts that some variants can use both.
https://www.notebookcheck.net/The-iPhone-13-Pro-Max-is-found-to-be-able-to-use-30W-USB-PD-to-charge-to-100-in-86-minutes.566235.0.html