The wording your usage here seems to suggest that the phones can be configured to not connect to 2G networks. This is false if you live in the USA. The phone will not connect to 2G networks regardless of any setting. There have not been any to connect to for a while now. The only thing out there that is 2G any longer is malicious actors.

It should come as no small surprise that phones in the US markets ship with a feature that is a de-facto backdoor.