Does Iphone use 4 g

4G and LTE are the same thing, so if it displays either you are using 4G. And your SE supports 4G/LTE, whether it is a 1st or 2nd generation SE. However, you should be aware that the major US carriers are all switching to Voice over LTE (VoLTE) as the only protocol they will support, and when this happens you won’t see any options in Settings/Cellular to select a network. Many non-US networks are making this change also.

Yes, at least here iPhone SE support 4G network.

Check -> go to Settings -> Mobile Network -> Mobile data options -> Calls/Voice and Data.

2G, 3G, 4G, LTE, VoLTE, 5G (iPhone 12 and later) all are Carrier Specific features. Contact your Carrier (Cellular Service Provider), the agency that issued the SIM / eSIM to you.

See the Pic below and explanation thereof