Yes, when you add a new calculated column or a measure, the formula bar in Power BI can expand to cover the entire screen, which can be frustrating for users. However, there is a way to adjust the number of lines that are visible when you expand the formula bar.
To do this, click on the downward arrow at the bottom of the formula bar, and select "Options" from the drop-down menu. In the options dialog box, you can adjust the number of lines that are visible in the formula bar when it is expanded.
Simply adjust the "Maximum Lines" setting to your desired number of lines, and click "OK". This will limit the expansion of the formula bar to the number of lines you have specified, making it easier to work with.
