No. <p1> and <p2> are not HTML tags. CSS can only style HTML elements.
Here's what you can do.
<html>
<head>
<style type="text/css">
p#paragraph1 {
font-size:14px;
font-family:times new roman;
}
p#paragraph2 {
font-size:20px;
font-family:times new roman;
}
</style>
</head>
<body>
<p id="paragraph1">Some text</p>
<p id="paragraph2">Some more text</p>
</body>
</html>
In the CSS, p#paragraph1 sets the style for the <p> HTML element with an id of "paragraph1". You can do this for all HTML elements.