http2 https://http2.github.io/faq/ can be turned on/off per domain from XtendWeb’s cPanel UI
Note that the protocol will be active only for TLS enabled websites over https://
Also since the protocol is enabled on a per IP basis. enabling at least on one vhost makes it active on the other namebased vhost
on the same IP address. Thus user level control is guarenteed only for domains with dedicated IP address.
You can test websites online using : https://tools.keycdn.com/http2-test