Hey Luke!

Volumes would be more ideal than Spaces for this need, as it would act much like plugging in a second hard drive to the droplet. You can format it and mount it to your preferred location. Note that this will not increase the size of the root partition, but you could use it to store data on. Popular examples might be to mount it as /home or /var/www. We have some great documentation that can get you started:

https://www.digitalocean.com/docs/volumes/

Now, if increasing the size of the root partition is the goal, then you would need to resize the whole droplet. For that, we have documentation here:

https://www.digitalocean.com/docs/droplets/how-to/resize/

Kind Regards,
Jarland

The previous commentator has covered the salient points. I would just like to add that setting up Volumes with your Droplet is a seamless affair since we allow for auto-formatted and mounted Volumes. This means that you can provision additional storage for your Droplet without having to run any manual configuration steps through SSH.