how to change 8.0 to 7.3 php version in ubuntu code example

Example 1: update php version ubuntu 7.3

sudo apt-get install software-properties-common
sudo add-apt-repository ppa:ondrej/php
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install -y php7.3

Example 2: how to change php version 8 to 7.1 in ubuntu 20.04

$ sudo apt install python-software-properties
$ sudo add-apt-repository ppa:ondrej/php