Please check the bandwidth that you are getting. Disable WiFi before running this Field Test.
You may check the current LTE band/5G/4G/3G by dialing *3001#12345#* pressing the call button and then selecting the Serving cell info option
Bandwidth on the 2nd and 3rd Screenshots.
See the pic below which is self-explanatory
E, 2G, 3G, 4G, LTE, VoLTE, and 5G all are Carrier Specific features. Contact your Carrier (Cellular Service Provider), the agency that issued the SIM / eSIM to you. About the LTE options on your iPhone - Apple Support (IN)
See the Pic below and the explanations thereof
The pic below is self-explanatory
However, iPhone model-specific feature is listed here --> Identify your iPhone model - Apple Support . and tap on "See the Technical Specs for Model "XXXXXX" under each model and Scroll down to the "Cellular and Wireless" section.