You would like to get a list of the available images in Digital Ocean, in order to be able to use them in creating your Terraform IAC script.
By installing the command line tool doctl, (instructions here), according to the documentation (after authenticating) you can run:
doctl compute image list
But the available images are not listed. In order to be list all the images you have to add the –public option (as described here) :
doctl compute image list --public