How to implement Full screen

I’m just wondering how to implement a full screen button?

I don’t need to know how to create the button itself I’m just not sure how to allow a publisher or subscriber to set a full screen view on the stream.

I’m assuming for example I would have to unpublish the publisher or subscriber respectively and republish with an option to set full screen? Just can’t find the option for it. I’m using openvidu browser 2.20 at the moment but will be upgrading to 2.22

Fullscreen is just a plain JS/CSS feature: How To Change The Browser To Fullscreen with JavaScript
OpenVidu does not really intervene in this matter.