Open Settings
Tap General
Tap iPhone Storage
Review unknown or suspicious apps
Tap VPN & Device Management
Remove any profile you do not recognize
Tap Privacy & Security
Check for unusual app permissions
Tap Battery
Look for apps using abnormal battery power
Tap Cellular
Check for apps using unexpected data
Tap Safari
Clear history and website data
Tap General
Tap Software Update
Install the latest iOS update
Tap General
Tap Transfer or Reset iPhone
Tap Reset
Tap Reset All Settings if needed
If suspicious activity continues, back up your data and erase the iPhone