How to run a Javascript file in an iframe in WordPress?

Hi All, I don’t even know if this is the correct forum to post this- basically I have an existing site, https://www.capintec.com, we want to add something called a decay calculator to it. I couldn’t find a plugin that behaves like one, so our software developer is going to create one in Javascript. But he wants me to create an iframe of some kind on a page, and somehow get the calculator to appear in that frame! Is this at all possible in WordPress? I tried searching for an answer but I don’t think I even worded it correctly when searching, because I don’t really understand what I am looking for -____-. I’m sorry, thanks in advance for any help, it is appreciated!