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.

https://ma.ttias.be/centos-7-4-ship-tls-1-2-alpn/

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.