Install PHP 7.4

Install PHP

sudo apt install -y php7.4 php7.4-fpm php7.4-mysql php-common php7.4-cli php7.4-common php7.4-json php7.4-opcache php7.4-readline php7.4-mbstring php7.4-xml php7.4-gd php7.4-curl

systemctl
Enable startPHP php7.4-fpm

to run as a service

sudo systemctl enable php7.4-fpm

Start the PHP service

sudo service php7.4-fpm start