Custom JavaScript

The same with custom CSS, not much to say here, if you want to custom JS, it's mean you know what you are doing.

But be careful, custom JS is very powerful, it can allow you to change the behavior of the website, or even leak your data. So only do it if you know what you are doing.

In some use cases, I use custom JS to remove the annoying cookie banner, ads, popup, ....

The best case is allows another plugin to interact with the embedded website.