If you are creating a new WordPress site on a server already running others and you’re not able to access permalinks that are specified without index.php in them, you may have AllowOverride off in /etc/apache2/apache2.conf

You can specifically enable it with a Directory directive to allow overrides (in .htaccess, which is where WordPress will place them.)

# /etc/apache/apache2.conf
<Directory /YOUR_PATH_TO_YOUR_WORDPRESS_DIR_GOES_HERE/>
        Options Indexes FollowSymLinks
        AllowOverride All
        Require all granted
</Directory>

# `service apache2 reload` after saving