New Outlook 2023

In the old outlook, there was a way to have your outlook theme in dark mode but the message pane by default in light mode.

In the new outlook, this setting seems to have gone missing or I could not see it for the life of me. I can switch the message pane to light by clicking the "sun" icon but that means I have to do it for every email I open and create.

Is there a setting somewhere that I have missed? I've been on it for 2 weeks now with no luck. I would like outlook to be in Dark Theme but the message pane to be in Light mode by default. Any help would be greatly appreciated.