Unless you financed through AT&T, it will be unlocked.
Reference: FAQ on Appl website
Nearly all iPhone models sold on apple.com are “unlocked” — which means your iPhone isn’t tied to a single carrier. If you choose carrier financing from AT&T or Verizon, your iPhone will be tied to your carrier, which may also include limitations on the eSIM.
I didn’t do financing thru the carrier, I have a prepaid plan. I just ordered at 3:15am est and forgot which selection I chose since I was half asleep and had a couple windows open. That’s good info tho re: eSIM