Why Windows Defender in Windows 10 in S mode does not provide an option to do a quick/full system scan?

[N Y from New York]

I just bought a new laptop running Windows 10 in S mode. Unlike a regular version of Windows 10, Windows Defender in Win 10 S mode does not let users to do a quick/full system scan, and a custom scan on a specific folder/file. My work requires me to access to third party USB flash drives from other people, I really want to scan those flash USB drives to make sure they have no virus/malware before I access the data on them. Unfortunately, I cannot find the scan option in Windows Defender on my laptop running Windows 10 in S mode. I really makes me nervous each time when I plug in a USB flash drive from someone else. Can anyone show me how to scan files in Windows defender on machine running Windows 10 in S mode?

Thank you very much for help.

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