I followed my previous tutorial until I had to use these additional commands to continue. There was a DOS installation that I chose the default/recommended answers wherever I was in doubt and I chose to keep my original configuration on one of the DOS pages. The packages below I found by using the commands in my previous tutorial. I did a find-replace to update the numbers on each of them from 7.4 to 8.0.

sudo apt install php8.0-apcu php8.0-bcmath php8.0-bz2 php8.0-cli php8.0-common php8.0-curl php8.0-dev php8.0-fpm php8.0-gd php8.0-gmp php8.0-imagick php8.0-imap php8.0-intl php8.0-mbstring php8.0-mysql php8.0-opcache php8.0-pspell php8.0-readline php8.0-soap php8.0-tidy php8.0-xml php8.0-xmlrpc php8.0-zip

sudo apt install dh-php

sudo dpkg -l | grep php | tee 2021-03-13-packages-second.txt

sudo apt install php8.0-fpm
sudo a2enconf php8.0-fpm

To activate the new configuration, you need to run:

sudo systemctl reload apache2

To enable PHP 8.0 FPM in Apache2 do:

a2enmod proxy_fcgi setenvif
a2enmod php8.0 

php -v

Now going to purge all older modules:

sudo apt purge php7.4* 

sudo apt purge libapache2-mod-php7.4

https://thishosting.rocks/install-php-on-ubuntu/
Refer to: How to change the PHP version you’re using

Now the rest of the steps after you’ve finished the steps from above:

sudo update-alternatives --set php /usr/bin/php8.0

sudo php -i | grep "Loaded Configuration File"

Loaded Configuration File => /etc/php/8.0/cli/php.ini

Run: sudo /etc/init.d/apache2 restart to actually update the media file upload size after making changes to the PHP.ini file, all other apache2 restart/reload cmds did not work