Instead of having multiple PHP installed locally, please use DDEV.

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Taken from the next post: https://tecadmin.net/install-multiple-php-version-apache-ubuntu/

Apache installation

sudo apt update 
sudo apt install apache2 libapache2-mod-fastcgi 

# Ubuntu 18.04 Users:
sudo apt install apache2 libapache2-mod-fcgid

PHP Installation

# On Ubuntu 16.04  
sudo apt install python-software-properties
sudo add-apt-repository ppa:ondrej/php

# On Ubuntu 18.04  
sudo apt install software-properties-common
sudo add-apt-repository ppa:ondrej/php

Install any needed version

• Let's take version 7.2 for example:

  apt update
  sudo apt install php7.2 php7.2-fpm
  

Restart the php-fpm services per version

sudo systemctl status php7.2-fpm

Apache configuration

Modify the virtual host that should use a specific version, add the next to it:

<VirtualHost *:80>
    <FilesMatch \.php$>
        SetHandler "proxy:unix:/var/run/php/php7.2-fpm.sock|fcgi://localhost"
    </FilesMatch>
</VirtualHost>

Restart the apache

sudo systemctl restart apache2

Install php packages per version

For each php package/extension, need to install per version.

For example, mysql or gd or tidy or curl:

sudo apt install php7.2-mysql
sudo apt-get install php7.2-gd
sudo apt-get install php7.2-tidy
sudo apt-get install php7.2-curl

Switch between version

sudo update-alternatives --config php

Personally, I add an alias to ~/.bashrc to easily switch:

alias phpswitch='sudo update-alternatives --config php'