How can I create subscriptions for specific variants only?
To create a subscription group for only specific variants, you can separate and select your desired product variant(s) in the product selector when creating your subscription group. To do this, click on the linked variants displayed under the product name.
See how to create a standard subscription group here: https://support.boldcommerce.com/hc/en-us/articles/360051203791-Create-a-Standard-Subscription-Group
Please note that variant level subscription groups are compatible with Online Store 2.0 themes only.