Hey @Dylan, your assumption is correct that autopublish is on by default and from there it’s managed at the product level in the admin. As far as I know, I don’t know if that was previously available as a setting.
From the help center here:
When you add a sales channel in Shopify, all your existing products are automatically available to the channel. If you don’t want to sell a product on a particular channel, then you need to remove the channel from the product’s availability.
Related thread here as well: Prevent product publication after sales channel install - #2 by KyleG-Shopify