No there isn’t as pretty much all developers would either have an iframe of their own to put the build in or would not want it an iframe of their own.
In your case, I would create another basic HTML page that does a full screen iframe and link to your PlayCanvas build.
At one point, we were looking at removing the iframe from the published build altogether.
Side note, if you had /e before the /p or /b in the published build URL, you get the iframe-less URL so you can test/use that instead.