nginx is not shipped by RHEL so you are probably pulling from epel. you can also pull the latest stable version directly from nginx's repo http://nginx.org/en/linux_packages.html#RHEL-CentOS which has supported http2 since RHEL 7.4 when they released alpn support in openssl.
you can also install the latest version of apache from red hats software collections repo that supports http2 but it throws everything into /opt/rh/rh-httpd24/ which is a bit weird.