On Android, the settings vary slightly from one model to another and from one Android operating system to another. Below you will find the most common settings found to enable LTE.
Alternatively or if none of these options apply to you, visit the
Mobility support section
for self-serve emulators/simulators to explain how to enable LTE on your device.
Select your device brand and model and search for "Accessing mobile network settings" for instructions on how to enable LTE.