No IT Auditor ever tests this, the just ask and if you say yes they move on. To actually test this you would have to statically sample a random sample of devices and confirm the antivirus is installed.

Instead that auditors are going to ask for a list off devices enrolled in the antivirus and a list of all devices (if the company even has an asset inventory) and see if they look right. But, most like the asset list will come from the antivirus enrollment and it won't matter.