Send variable from page URL to iframe src

I currently have a redirect to http://www.myWPsite.com/specificPage/?theVar=passedVariable. This redirects to a WP page with an iFrame on it. What i need is the iFrame src to be set to http://www.someOthersite.com/?var=passedVariable. So I need the variable in the URL to be sent to the SRC parameter in the iFrame. Is this something this plugin can do? I can’t say I fully understand the description of this plugin to know for sure. If you need clarification please let me know, I can give more example code.

https://ww.wp.xz.cn/plugins/advanced-iframe/