Install php and php modules on Ubuntu 18.04 for wordpress

install php for wordpress
sudo apt install php libapache2-mod-php php-mysql

install other php modules that required for wordpress
sudo apt install php-curl php-gd php-mbstring php-xml php-xmlrpc php-soap php-intl php-zip

grant highest priority in apache2 server for the php files

IfModule mod_dir.c
IfModule

Restart apache server
sudo systemctl restart apache2

Chek status of the apache2
sudo systemctl status apache2

Test php on your localhost

phpinfo();