Bug Report :
Current setup - Playing the game off a laptop and secondary screen.
Secondary screen is plugged in and set to primary monitor in display settings so the game will run off of that, the Resolution for the monitor is 2560 X1440 and the laptop is 1920X1080.
If you close everything back to Steam, unplug your laptop from the secondary monitor to be the only monitor remaining, and then just run Baldurs Gate 3 it will launch using the UI scaling and resolution of the primary set monitor AKA 2560X 1440. In game settings, it says its only running in 1920 X 1080 but the game will run and only display the top left hand corner of the screen as its over scaled way past the size of the new display.
This makes it impossible to use most of the screen or change the settings from the menu.
Hope you can recreate this or it helps at all.