@Richard Berry, Thanks for posting in Q&A. From your description, I know you have some questions with uninstalling win32 app. Here are my answers for your reference:
Q1: Sideloaded WIN 32 apps - do they update automatically?
A1: For Zoom, because it was deployed via win32 app, it will not update automatically. To update the win32 app, we can use Win32 app Supersedence to update the app.
Here is a link with more details: https://learn.microsoft.com/en-us/mem/intune/apps/apps-win32-supersedence
Q2: Do I uninstall the original version before installing the new version? What happens if I just assign a new version without uninstalling, does it just over-write the old version?
A2: Whether you should uninstall the original version before the new version or what happens if you assign a new version without uninstalling, it is just up to the app itself, you should contact the app developer to confirm. You can also manually test on one device to see the update behavior, if the installation can run successfully, it means no need to uninstall the original version and the new version will over-write the old version, you can set the Uninstall previous version No under the Supersedence behavior settings in Intune. If the installation can not run successfully, it means that you need to uninstall the old version before you install the updated version, and the new version does not overwrite the old version, you should set Uninstall previous version Yes under the Supersedence behavior settings in Intune. You can refer more information with the link above.
Hope above can be helpful, Thanks.
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