If you have a third party AV installed, the only thing you should be able to do with Windows Security is to request an offline scan. The installation of a third party solution has, for years, disabled the built-in features of Windows Defender/Security.
When you open Settings, Update & Security, View Update History, scroll down to the Definition Updates section, expand it, and look at when the last definition update was applied and report back. The last one on my system. which is pretty much on 24/7, is KB2267602 with Version 1.351.526.0, that has a date of 10/16/2021.
Please report back on what the last definition update was as a starting point.