If you’re using DigitalOcean’s WordPress image to deploy a Droplet, then you won’t specifically need to install any additional modules or extensions, unless you’re wanting to add Memcached, Redis, etc (or other extensions from the PECL repository).
WorddPress only requires a compatible PHP version, MySQL (or MariaDB / Percona) and a Web Server such as Apache, NGINX or Caddy (to name a few).
Currently, the latest release requires at least PHP v5.6 or greater and MySQL v5.5 or greater.
Link: WordPress Requirements
Are you looking to use DigitalOcean’s pre-configured image or are you setting up the server on your own? If so, what web server are you using (NGINX, Apache, Caddy etc)?