Subscription App suggestion or API setup guide

[104Ant]

Hi, 

I've been researching for a subscription application that will allow a free trial for a week with Variant A (SKU: XYZ-Trial) then start billing after 7 days with the full subscription product of Variant B(SKU: XYZ-Full). But I didn't find a recurring payment app that allows two variants.
Note: Trial product and Full subscription product are different (trial product is a sample fo a full product)

I've noticed Shopify Subscription API has been rolled out in Jan 2021, but still couldn't see if the option above is possible.

Any App suggestion or API guide will be greatly appreciated.

Thank you