If you click on the page you want to have different URLs you can add the URL in the location tab.
If i was to add /about/contact to this page and then went to that URL it would take me the canonical that i set so in this context /contact-us
If you still want the page to be available at the /about/contact url you can make an alias of the page in the sitemap. Just pick the page and then move it to the new location in the site and it will ask if you the following