How to reduce third-party code on Wix

Dear Wix Community,

I am a newbie on Wix and would like to improve the performance of my website.

By using PageSpeed Insights, it shows the following warning messages: "Reduce the impact of third-party code " and “Reduce the work of the main thread”

I understand that can be partially solved with adding some code on JS files. However, how to have access on JS files on Wix?

Any help or support on this matter would be highly appreciated. Thank you.