Hi Leon,
The short answer is no, you don’t need an antivirus, but you should:
- Not jailbrake the phone.
- Ensure the phone’s operating system iOS is up to date and latest version.
- Ensure the installed apps are up to date.
- Be mindful what apps you install on the phone. Use apps only from trusted vendors.
Here are some good guidelines with more detail:
https://www.cyber.gov.au/protect-you...r-mobile-phone
Hope above is helpful.
PS: If you don’t know what jailbrake is, then you probably don’t have it and don’t have to worry about it