Normally all URL opens up in a new tab. If you want to open it in the popup, you would have to create modal window (using web qweb and JS) to display the content of the URL.

The simple way to do this without web development,  create a wizard and in the XML use "iframe" tag to show the content of the URL.

<record id="my_wiz_view" model="ir.ui.view">
 <field name="name">my.wiz.popup.view</field>
    <field name="model">wiz.popup</field>
    <field name="arch" type="xml">
        <form>
             <iframe src="https://www.w3schools.com"></iframe> 
        </form>
    </field>
</record>