If you want to schedule something that runs without you having to turn on your computer, you would need to do a cloud flow with an Office Script (I'm not sure if an office script can refresh Power Query, but I guess it should). This would require a premium license of Power Automate ($15/month).
Desktop flows run on the desktop, so they cannot run without having a machine available, unless you run it on a virtual machine on a server. So, this is a cloud flow question. Please post it in here: https://powerusers.microsoft.com/t5/Building-Flows/bd-p/BuildingFlows
If you do want to do it in Power Automate Desktop, you will still need a premium license to be able to schedule your flows (either via Windows Task Scheduler or via a cloud flow that runs on a schedule and calls a desktop flow). Your machine will need to be on for it to run. You can then either do it via the user interface of Excel (not recommended) or via scripting, such as PowerShell or VBscript.
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