The EFF says the feature is only available on newer devices "due to limitations of old hardware." Mishaal Rahman also noted that you'll need to update your device to the Radio HAL version 1.6 to access the kill switch.
However, most devices that are being upgraded from Android 11 don't support the latest Radio HAL due to Google Requirements Freeze, per XDA Developers.
Unfortunately, this feature requires version 1.6 of the Radio HAL, and many devices don't have that.
That said, this should not bother owners of devices running Android 12 out of the box.If you have a Google Pixel 6, for example, you can turn off 2G by navigating to Settings > Network and internet > SIMs > Allow 2G.
In celebration of the new Google Pixel 6 hitting shelves, we've rounded up a list of the best USB-C compatible car chargers for Google Pixel 6 on the market right now