Thank you for reaching out to us. As I understand you are looking for an option to change AIP/Sensitivity tab within office apps for one of the user.
Unfortunately there is no option to change the ribbon size within office apps.
Also I see you are using Unified labelling client, the Azure Information Protection unified labeling client has moved into maintenance mode as of January 1, 2022. Moving forward, no new features will be added to the unified labeling client.
I recommend that you use the default labeling that's built-in to Office apps for the extra stability, better performance, and latest features. If you have the AIP unified labeling client installed, you'll need to disable the AIP add-in for Office apps.
How to disable the AIP add-in to use built-in labeling for Office apps - https://learn.microsoft.com/en-us/microsoft-365/compliance/sensitivity-labels-aip?view=o365-worldwide#how-to-disable-the-aip-add-in-to-use-built-in-labeling:~:text=Sensitivity%20labels%20sections.-,How%20to%20disable%20the%20AIP%20add%2Din%20to%20use%20built%2Din%20labeling%20for%20Office%20apps,-When%20you%27ve%20installed
Would suggest to use the default/native labelling client check the experience with the user. Also you can try this approach like creating a new tab within office apps ( for example word application ) and move the sensitivity option within that tab, reference below screenshot
Let me know if you have any further questions.
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