How to install/enable intl and xsl extensions after installing PHP 7

You can run sudo apt-get install php7.0-intl to get it installed. You dont need PPA adding on 16.10 .

If it is for dev purposes only, the easiest way would be use a PPA like ppa:ondrej/php-7.0 and then apt-get install php7.0-intl and apt-get install php7.0-xsl. PPAs should NEVER be used in production.