Draw a custom line using the Line Segment Tool () or Pen Tool (P) . This allows you to change the stroke weight, color, and dash style independently of the text. Hold Shift while drawing to keep the line perfectly horizontal.
Alternatively, you can also use the following method: illustrator text underline
: Use two simple clicks to define the start and end points of your underline. This allows for more organic or slanted designs. 3. Advanced Appearance Method Draw a custom line using the Line Segment