The Debian default repository does not contain latest PHP. But it can be installed via PHP repository
Why Debian system doesn't contain latest software?
Debian is a stable and reliable distribution that prioritizes stability and security over new software releases. The latest software may contain bugs or security vulnerabilities that have not been fully tested, and including them in the distribution could compromise the stability and security of the system. Instead, Debian focuses on thoroughly testing and integrating stable releases of software into their repositories, ensuring that users have access to high-quality and secure software.
Install file dependencies
sudo apt install -y gnupg2 ca-certificates apt-transport-https software-properties-common
Add PHP repository
echo "deb https://packages.sury.org/php/ $(lsb_release -sc) main" | tee /etc/apt/sources.list.d/php.list
wget -qO - https://packages.sury.org/php/apt.gpg | apt-key add -
Install latest PHP and some modules ( at this time 8.0 is the latest version)
sudo apt update
sudo apt install -y php libapache2-mod-php php-pear php-cgi php-common php-mbstring php-zip php-net-socket php-gd php-mysql php-bcmath unzip wget git
Now check the PHP version with this command
php -v
