The download page says that Pg 14 is available for RHEL 6

(Yes, it's old.  Out of my hands.  But I can influence getting off of Pg 9.6.)

We have to manually install RPMs, since the server isn't directly connected
to the Internet.

https://www.postgresql.org/download/linux/redhat/

Select version:
     14
Select platform:
    Red Hat, CentOS... version 6
Select architecture:
    x86_64

It says this:

# Install the repository RPM:
sudo yum install -yhttps://download.postgresql.org/pub/repos/yum/reporpms/EL-6-x86_64/pgdg-redhat-repo-latest.noarch.rpm

# Install PostgreSQL:
sudo yum install -y postgresql14-server

However, the .noarch.rpm doesn't mention v14, so I poked around more and saw
links for direct download at the bottom of the page.  It says that only v12
is the max available for RHEL6

It's only when you go down to the very bottom that there's a link showing
that v12 is the last to have pre-built binaries for RHEL 6.

Are there actually Pg 14 binaries for RHEL 6?

--
Born in Arizona, moved to Babylonia.