Sorry, finding it for free legally can be tough. Sometimes, it might be available on free trial periods of certain streaming services. But usually, you'd have to pay on platforms like Amazon Prime Video or Disney+ to watch it legally and with good quality.
You might find it on some illegal streaming sites, but that's not recommended as it's against the law and can have risks. It's best to check legal streaming platforms like Netflix or Hulu, though they might require a subscription.
I don't think there's a reliable and legal way to watch 'A Cinderella Story: Starstruck' online for free. You could look for discounts or promotions on legitimate streaming sites, but free and legal options are rare. It's worth investing in a subscription for a better viewing experience and to support the creators.