How do I change the size of the legend key in a chart?

[BicyclePatty]

On a column chart in Excel each column has a different color. The name of
each category is shown in the legend along with a small box (legend key) with
the color corresponding to the color of the column for that entry in the
chart. My question is how to I enlarge those little color boxes next to the
names in the legend? My color boxes are so small I can't see what the color
is. Color boxes are way smaller than font size on the adjoining text.

 

[Jon Peltier]

Generally the boxes scale with the font size. One thing you may consider is
using an unfilled box, that is, setting the border of the series to No Line.
The black outline isn't necessary if you use colors which are not too light,
and removing it will allow the color to show clearly.

- Jon