Style Switching

You have to use Conditional Tags, with those, you can check in which page you are, and load a diferent stylesheet for each option.

A little example using is_page

if(is_page('about')){

echo '<link href="https://wordpress.stackexchange.com/questions/161615/style1.css" rel="stylesheet" type="text/css" />';
} else {
echo '<link href="style.css" rel="stylesheet" type="text/css" />';
}

That should go in your header.php file, or you could create diferent headers for diferent pages, and then use the get_header function. There are other ways to deal with headers, but that’s a diferent topic.