Upgrade PHP or remove php Debian

First install Sury php package repo

#!/bin/sh
# To add this repository please do:

if [ "$(whoami)" != "root" ]; then
    SUDO=sudo
fi

${SUDO} apt-get update
${SUDO} apt-get -y install lsb-release ca-certificates curl
${SUDO} curl -sSLo /usr/share/keyrings/deb.sury.org-php.gpg https://packages.sury.org/php/apt.gpg
${SUDO} sh -c 'echo "deb [signed-by=/usr/share/keyrings/deb.sury.org-php.gpg] https://packages.sury.org/php/ $(lsb_release -sc) main" > /etc/apt/sources.list.d/php.list'
${SUDO} apt-get update

Upgrade PHP or remove php Debian

Remove older version of PHP

apt remove php7.4-cli php7.4-common php7.4-curl php7.4-fpm php7.4-gd php7.4-intl php7.4-mbstring php7.4-mysql php7.4-opcache php7.4-readline php7.4-soap php7.4-xml php7.4-xmlrpc php7.4-zip

apt purge php7.4-cli php7.4-common php7.4-curl php7.4-fpm php7.4-gd php7.4-intl php7.4-mbstring php7.4-mysql php7.4-opcache php7.4-readline php7.4-soap php7.4-xml php7.4-xmlrpc php7.4-zip

Install/Upgrade to PHP7.4 or PHP 8.0

PHP 7.4

apt install php7.4-cli php7.4-common php7.4-curl php7.4-fpm php7.4-gd php7.4-intl php7.4-mbstring php7.4-mysql php7.4-opcache php7.4-readline php7.4-soap php7.4-xml php7.4-xmlrpc php7.4-zip

PHP 8.0

apt install php8.0-cli php8.0-common php8.0-curl php8.0-fpm php8.0-gd php8.0-intl php8.0-mbstring php8.0-mysql php8.0-opcache php8.0-readline php8.0-soap php8.0-xml php8.0-xmlrpc php8.0-zip