Turn on Safari pop-up blocking: Settings > Safari > Block Pop-ups
Turn on fraudulent website warning: Settings > Safari > Fraudulent Website Warning
Clear Safari history and website data: Settings > Safari > Clear History and Website Data
Close suspicious tabs in Safari
Delete suspicious apps
Remove unknown browser extensions: Settings > Safari > Extensions
Check notification permissions: Settings > Notifications
Turn off notifications for suspicious apps and websites
Disable calendar spam subscriptions: Settings > Calendar > Accounts > Subscribed Calendars
Remove unknown configuration profiles: Settings > General > VPN & Device Management
Update iPhone to the latest iOS version
Restart the iPhone
Use a trusted ad blocker in Safari
Avoid tapping pop-ups or fake download buttons
Reset Safari settings if ads continue
Reset all settings if the problem persists: Settings > General > Transfer or Reset iPhone > Reset > Reset All Settings