Yes. For instance, if the specific CSS file you want to use based on some program logic is in the variable $cssFile, then you could do the following:
<?php
$cssFile = "example.css";
?>
<html>
<head>
<title>Example</title>
<link rel="stylesheet" type="text/css" href="<?php echo $cssFile; ?>">
</head>
Or if you prefer:
<?php
$cssFile = "example.css";
// use herdoc string to echo output:
echo <<<EOD
<html>
<head>
<title>Example</title>
<link rel="stylesheet" type="text/css" href="$cssFile">
</head>
EOD;
// and so forth....
?>