Recently I had a project where I was to show a button based on an URL parameter. Oxygen Builder is my go-to tool for page building, and it has the native and outstanding Conditions function to show elements, from sections to spans, however there is no preset for URL parameters. So I was making a little digging, tried a few things, then I ended up using this solution on Stackoverflow (SO). For reference, I am attaching the relevant answer here, but you can find the whole dicussion on SO.

This post is about how to implement the solution above in Oxygen Builder.
Implementation
So I took the code and made a custom PHP function in Advanced Scripts:
function currenturl_callback() {
global $wp;
$current_url = home_url(add_query_arg($_GET,$wp->request));
return $current_url;
}
Some explanation:
- currenturl_callback is the name of the function chosen by me. You can write here any other unique name,
- current_url is the name of a variable I used here, as you can find also in the solution on SO. Feel free to modify it.
As a result we now have function to use in Oxygen’s Conditions, namely here:

Oxygen Conditions
The following images help you to find what to select and where you write to:


After this step you end up to see the final part of making the condition. You will see the following window.

And here it is all up to you. I used the contains condition, and then wrote the specific part of the URL I wanted to base my condition on.
Conclusion
This solution is working for me, and I hope you can use it too. Feel free to share your solution, or raise any questions about this method in the comments section. I try to answer them all. Cheers!