craft.entries and :first-letter
Rich Text fields always return the paragraphs wrapped in &lt;p&gt; tags. So you would have to use an additional &lt;div&gt; element and apply the dropcap styles to the first &lt;p&gt; tag within that &lt;div&gt; using the first-of-type pseudo-class.

&lt;div class='dropcap'&gt;
    {{ entry.body }}
&lt;/div&gt;




.dropcap p:first-of-type:first-letter {
  float: left;
  font-size: 4em;
  line-height: 3em;
}