I really though that's it's your question.
But now I see that it somewhat different.
What you are trying is the right approach, but you also need to open the session. And your syntax is wrong.
See
https://winscp.net/eng/docs/guide_custom_commands_automation
https://winscp.net/eng/docs/commandline
But now I see that it somewhat different.
What you are trying is the right approach, but you also need to open the session. And your syntax is wrong.
winscp /command "open !S" "get !& c:\Users\myName\Desktop\TEMP\*" "exit"
See
https://winscp.net/eng/docs/guide_custom_commands_automation
https://winscp.net/eng/docs/commandline