Hi there @ghostzicht, 

Thanks for sharing your question with us! Happy to help! 

While you can customize review widgets to a certain degree at this point, at this time, it is not currently possible to change the size of our stars. 

I have submitted a product feature request on your behalf to our product team. In the meantime, you may be able to attempt to have your site's CSS override the Klaviyo widget's CSS, but that is something you would need work with your developer on to see if this is a possibility for your store.

Thanks for participating in the Community!

-Taylor