I’m not familiar with the Cherry Framework but a quick search looks like the theme options allow for “Custom CSS” right under the General tab. To quote:
Custom CSS – if you need to add some CSS rules, but you don’t want to mess with the main CSS file, you can use this field. Just insert your new css rules.
Your other option is to use a child theme with a custom CSS file, like you mentioned. For just small CSS changes though, I don’t see any reason why the Custom CSS option of the theme wouldn’t work.