Build secrets and SSH forwarding

Is ssh host forwarding , introduced in Docker 18.09 supported in circle CI?
Here is an article for reference

I’m not familiar with SSH forwarding in a Docker context. Can you outline how you would want to use that in your CI system?

Whats the latest docker version supported by circleCI right now ?

I would like to use:
# syntax=docker/dockerfile:1.0.0-experimental syntax in the Dockerfile is that supported ?

This might help. Just found it browsing for other information: