Upgrading from Enterprise Linux 7.x (EL7) to the latest release 7.9 within a major version could be easy as long as the yum repository is the latest and healthy. Let's see the release number before upgrading.
[root@primary01 ~]# cat /etc/oracle-release
Oracle Linux Server release 7.5
[root@primary01 ~]# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 7.5 (Maipo)
[root@primary01 ~]# uname -a
Linux primary01.example.com 4.1.12-112.16.4.el7uek.x86_64 #2 SMP Mon Mar 12 23:57:12 PDT 2018 x86_64 x86_64 x86_64 GNU/Linux
It's enterprise linux 7.5.
Now we use yum to upgrade the whole operating system.
[root@primary01 ~]# yum upgrade
...
Or without asking anything.
[root@primary01 ~]# yum -y upgrade
...
Check the release number after upgrading.
[root@primary01 ~]# cat /etc/oracle-release
Oracle Linux Server release 7.9
[root@primary01 ~]# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 7.9 (Maipo)
[root@primary01 ~]# uname -a
Linux primary01.example.com 4.1.12-124.48.2.el7uek.x86_64 #2 SMP Tue Feb 9 14:03:44 PST 2021 x86_64 x86_64 x86_64 GNU/Linux
It's enterprise linux 7.9.