Increase the tab's font size.
You can leave the tab name(s) blank and insert your own text labels or text fields with a smaller font size afterward. Also set the tab width to a fixed width for this.
Or replace the tab labels with buttons sized to suit. The tab control itself might be replace with a Slide Control with the buttons serving as tab labels using go to object to select different panels. The slide animation can be disabled if you don't want that effect to appear when a button is clicked to select a panel.