Using New Outlook on Windows for professional communication and productivity
When you said "You are correct to be concerned about the attachment preview; by default, attachments now open in a preview pane before allowing you to open the file in its entirety."
The phrase "default" would imply that there is some other option, but then you go on to explain that there is not. This is the same answer as saying "it's a feature, not a bug", which is one of my favorite software developer responses.
To-date, I have been extremely underwhelmed with "NEW" Outlook. I feel that you (MS) took a lot of really nice features and functions and simply removed them for some unknown reason. Based on the comments and Google searches on "how do I...with "new Outlook" it seems like this is not a very popular "upgrade" nor is it intuitive.
While I try not to get stuck in my old ways of this is how we used to do it back in "2022" and try to evolve to new releases, cloud feature, etc. I would remiss if I didn't let you know that I as well as a large community of users (according to the Google searches) would agree that the NEW Outlook is severely lacking in some of the basic features that made/makes it such a valuable tool.