Open Settings
Tap Cellular or Mobile Data
Tap Cellular Data Options
Tap Voice & Data
Select 5G Auto, 5G On, or 5G Standalone if available
Make sure your carrier supports 5G
Make sure your SIM or eSIM is 5G-compatible
Turn off Low Power Mode if 5G is not activating
Restart your iPhone if needed
Check for iOS updates in Settings
Move to an area with 5G coverage