I cannot find a satisfactory answer to the question posed above. From what the app says, and the documentation, Avast Mobile only seems to scan and protect a network connection – and does not indicate it can scan your device to see if it is infected. Can someone please verify this? --Rick
Hi caseyrick 
Simple answer: No, because Apple doesn’t allow it.
That said, there is an ( one time paid ) app that offers some real time protection, and also guides that help you to secure iOS better :
https://apps.apple.com/us/app/iverify-secure-your-phone/id1466120520
I highly recommend it to novice - and average users.
Greetz, Red.