Your carrier can be found towards the top of the screen or on your sim card. Contact your carrier to verify if your phone is unlocked.
Verizon, AT&T, T-Mobile, Sprint, US Cellular, Other, Unlocked
Go to Settings > General > About > scroll down till you see Capacity.
128 GB, 256 GB, 512 GB
Click on each condition to determine what condition your device is defined as.
Flawless, Good, Fair, Broken, No Power