mattwm;1284367 wrote:. . .
How would I go about doing this,
. . .
When you say "this", do you mean restricting the number of blog posts displayed, or changing the font size?
To restrict the number of posts displayed to 3, you could edit the PHP code of the page for that section.
To change the size of the most recent post, you would have to edit the CSS style sheet. Perhaps create a special style for that particular element, and then on the PHP page that contains that element, wrap it in the new style you just created.