If you want to video in the loop then the parameters “?loop=1&playlist=GRonxog5mbw” have to be passed in iframe src after ”?”.
I have passed the youtube id in playlist parameters.

Example:

<iframe width="560" height="315" src="https://www.youtube.com/embed/q5jEY92Amgw?loop=1&playlist=q5jEY92Amgw" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>