The Apple Store can sell you a phone in one of two ways. SIM/Carrier free or you tell them your carrier and they activate it in the carrier which locks the phone to the carrier for 60 days. So you need to buy the SIM free version and activate/transfer your SIM/eSIM yourself.
Arc73 t1_jeezn1z wrote
Reply to comment by rLima_Peru---Mod in AT&T taking ownership of your owned device by [deleted]
The Apple Store can sell you a phone in one of two ways. SIM/Carrier free or you tell them your carrier and they activate it in the carrier which locks the phone to the carrier for 60 days. So you need to buy the SIM free version and activate/transfer your SIM/eSIM yourself.