I believe transform: scale is the way to do this, if at all: scale() - CSS: Cascading Style Sheets | MDN. As you mention, this may cause other issues in the app with tool tips and hover, etc. It’s not really a standard or well supported thing to do.
However, one thing to think about is browser sizes: it may look better slightly zoomed out on your screen size, but what about your users on larger or smaller monitors?
Another way to approach this is to change the font sizes across the board.