The only virus you need to be aware of is the one that can get on the outside of the phone when you touch it right after you shake hands with someone with covid19. Joking aside.
There are currently no known/widespread viruses for iPhones. What you are most likely to experience is SPAM in the form of calendars that are installed from the Internet. However, you will always be asked if you want to install the calendar, to which you simply answer no - and if you press yes, it can easily be deleted again afterwards. It does no harm, but can be annoying.
You may also experience some websites telling you with a pop-up similar to the iOS design that you have got a virus - however, this is also just fake, and only aims to send you on to the App Store so that you can download some useless app , which promises you everything from a virus-free phone to $1,000,000.
Quite short. Everything that happens in your apps stays in your apps. There are no 3rd party apps that have access to important system files in iOS, therefore the chance of viruses is quite small, if not non-existent.
The only place there might be a risk is if you jailbreak your iPhone. The chance isn't great either - but still. You open the system with jailbreak and make it possible to download things from 3rd party stores, Cydia, Sileo or directly from the internet. Things that can damage the system. However, jailbreaking is something you have to actively do, so it's not something you "get to"
So enjoy your iPhone and each not so worried.