Hi there,

Yes, it is possible to resize a volume via the DigitalOcean API:

https://developers.digitalocean.com/documentation/v2/#resize-a-volume

Another option is to use the doctl command-line tool:

https://docs.digitalocean.com/reference/doctl/reference/compute/volume-action/resize/

You could write a script that checks the usage of the specific disk and if the usage is higher than 80% you could use one of the above methods to resize the disk.

The command to get the disk usage percentage would look like this:

df -hl | grep '/you/mount/path/here' | awk '{print $5}'

Hope that this helps!
Regards,
Bobby