Yep, pretty much it!
So if you call it cron.php and add that to your theme file, then go to:
https://www.domain.com/wp-content/themes/theme-name/cron.php
It should run
Just backup your DB before running it, just to be sure.
Then check your posts to ensure it has the right dates.
As I say, depending on post quantity, this may lead to time out issues in the future! I’d therefore look into batch processing which can run without as many issues
