Yes, you can do this in a single droplet or in a multi-droplet configuration.

In in a single droplet config you will need to update your Apache config for your WordPress site updating the port number. This could be anything really that does not conflict with another service - for example 81 or 8080

Next you will need to install NGINX

• https://www.digitalocean.com/community/tutorials/how-to-install-nginx-on-ubuntu-16-04

Then to handle your SSL you would need to perform a setup like the following

• https://www.digitalocean.com/community/tutorials/how-to-set-up-nginx-load-balancing-with-ssl-termination

One change in the above is that you will be operating with only one application server (Apache) as your backend unless you decide to add more.