changing font size of individual words/lines

Hi there, is it possible using css code to make some paragraph text larger or smaller than the rest (like you can in MS Word)? I have certain lines that I’d like to make smaller print.

Also, I wanted to make the first few words in a paragraph bigger, as in some books (like the or commands), and tried putting the <h2> </h2> on both sides and it broke it as a paragraph. Any ideas on how to prevent that?

I looked it up on w3schools.com and all it showed was the CSS to define a header or paragraph style in the style sheet, not individual text. If it’s not possible to do individual text, could I create a p2 style, define it and then use that?

Thanks!