First, you need a server with Ubuntu 20.04. I will go with Umbrellahive.com's dedicated server.

then open as root - sudo su (optional)

apt-get update
apt-get install nano curl
apt install nano
nano /etc/cpupdate.conf

Here is the file format for the contents of this file: https://support.cpanel.net/hc/en-us/articles/360052251053-How-to-Install-a-Specific-Version-of-cPanel-WHM

CPANEL=release
RPMUP=daily
SARULESUP=daily
STAGING_DIR=/usr/local/cpanel
UPDATES=daily

what we do here is: https://docs.cpanel.net/changelogs/118-change-log/ (ref)

CPANEL=118.0.11
RPMUP=never
SARULESUP=never
STAGING_DIR=/usr/local/cpanel
UPDATES=never

now: https://docs.cpanel.net/installation-guide/install/ (ref)

cd /home && curl -o latest -L https://securedownloads.cpanel.net/latest

then

sh latest --force

Done!

you successfully installed the panel :)

WAOO!

tested Out

root@x.x.x.x:~# curl -s http://httpupdate.cpanel.net/cpanelsync/TIERS | grep ^[c-s]
edge:11.122.0.2
current:11.120.0.14
release:11.120.0.14
stable:11.120.0.11
lts:11.118.0.13
root@x.x.x.x:~#