Android 12 adds an option to deactivate 2G for security reasons, but your phone may not allow it - Android Police
A tweet by Mishaal Rahman notes that a new change was spotted in Android 12 in the form of an option to disable 2G modems on phones (per the EFF).While the feature arrived on Android 12, not all devices running the latest OS version can use it.The 2G kill switch requires an update to the Radio HAL version 1.6, which many devices coming from Android 11 are skipping out on because of Google Requirements Freeze (GRF).
However, devices launching with Android 12 — and even newer Pixel and Samsung phones — will be able to take advantage of the feature.