With All-Inkl, you do not have to switch the whole account to a new instance. Make sure in your KAS-domain-settings your domain has PHP 7+ selected.
In CLI (Commandline-Interface) try following command:
/usr/bin/php72 /www/htdocs/youraccountnumber/yourpathtonextcloud/console.php nexcloudcommand
Change yoursomething to your needs et voila.
@dschafar87 change path to PHP in your script to
/usr/bin/php72
this should work.