We don’t offer such a functionality by design as we like to get user aware on the update and watch the output. Sometimes there are important in formation changes done or needed software reinstall.
For interactive execution, you might need to export G_INTERACTIVE=0 [howto] call dietpi-sync 1 without user interaction - #5 by MichaIng to avoid user input.
For apt package updates, we offer a build-in functionality. No user own script or cron would be needed.