Hey!
Wix elements and components (like Wix Stores) are proprietary, thus the only control you have over them is what they give you.
You could create your own alternative and then you would have the ability to customize more features.
For now you can see what is possible to customize in Wix Stores for the checkout page but everything else is a feature request for now:
https://support.wix.com/en/article/request-customizing-the-checkout-page-in-the-wix-stores
You can contact support for more info on this:
https://support.wix.com/en/article/contacting-wix-support