Open the Settings app
Tap General
Tap About
Check the model name
Check the model number
Check the serial number
Check the iOS version
Check the storage capacity
Check the battery health in Settings
Check the screen and buttons for damage
Check Face ID or Touch ID
Check the camera and speakers
Check Wi-Fi and cellular connectivity
Check the IMEI if needed
Check Activation Lock status
Check the battery cycle count if available
Check for software updates
Check the Apple warranty status
Check the Find My iPhone status