How Do I Add the <Link> tag into <Head> on a Page?

You can add any plugin code for a specific page in the page settings. To do this, right-click the page and select Settings. Then go to the "Custom Code" tab, click on the "+" icon, and select <Link>. Screenshot:

After that you will need to give a name to this link and fill in the necessary fields based on the URL which you're plugging in. For example, I plugged in Google Fonts in the screenshot:

Before, this code looked like this: <link rel="preconnect" href="">