$ sudo rpm --import https://rpm.opera.com/rpmrepo.key
$ sudo tee /etc/yum.repos.d/opera.repo <<RPMREPO
[opera]
name=Opera packages
type=rpm-md
baseurl=https://rpm.opera.com/rpm
gpgcheck=1
gpgkey=https://rpm.opera.com/rpmrepo.key
enabled=1
RPMREPO
$ sudo yum -y install opera-stable

Tested on Fedroa 34

Reference: https://www.tecmint.com/linux-web-browsers/