Free Trial of Paid Membership

I know that this used to be a thing, but I can’t figure out how to do it in Ghost 4.6.x (or 4.5.0). Is there a way to do automatic free trials with Stripe?

I know I could probably set it up myself if directed to the correct configuration file as well. I understand the Stripe API pretty well but have trouble getting through the Ghost files and finding what I need there.

Any guidance is much appreciated. Thanks!