You can recommend products in a particular collection using product tags.
For example, when your customer receives a review request for the product iPhone 8, you'll probably want to recommend products in the collection "iPhone Accessories".
In This Guide
Adding The Tag To Recommend Collection
1) Go to the Product Page in Shopify Admin
2) Tag the product with "stamped-recommend-collection-{collectionId}". Replace {collectionId} with the Collection's ID ( You can find the ID in the URL when editing the Collection in Shopify Admin)
Example:
3) Done
When a customer receives a review request for the above product, it'll recommend products inside the Collection ID stated above.