@Austin ,
> programmatically get the latest build versions for each update channels
1 What does "programmatically get" mean? Could you please explain more information about this?
Please note, the issues related to code or scripts are out of my support scope. We are mainly responsible for general issues of Office desktop applications.
2 Besides, do you want to check the latest version number or do you want to install the latest version updates?
Generally, if you need to check the latest version number of Microsoft 365 apps of different update channels, please open this article "Update history for Microsoft 365 Apps (listed by date)". For convenience, please add the bookmark for this webpage on broswer.
The updated version would be applied to the whole Office apps not only to Excel apps.
If you want to intstall the latest updates versions to do some test, Microsoft 365 apps are enabled automatic update by default. There would be a scheduled task named “Office Automatic Updates” checks for updates on a regular basis automatically.
You may go to one Office app > File > Account > Update Options > Update Now, it would check updates.
After getting the latest version numbers, you could also enter the below commands in Run dialog for different update channels of Office. I would make the architecture of 64 bit as an example.
"C:\Program Files\Common Files\microsoft shared\ClickToRun\OfficeC2RClient.exe" /update user updatetoversion=16.0.XXXXX.XXXXX
Any updates or questions please free to post back.
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