Path param explained :

• subscriptionId Id of the subscription. This can be passed in the following format :
  • {id} - where id is the Loop internal id of the subscription contract. This is the default path param format.
  • loop-{id} - where id is the Loop internal id of the subscription contract.
  • shopify-${id} - Where id is the shopifySubscriptionId of the subscription contract.

Key points to consider:

Single-Line Subscription

• If the upgrade profile has multiple products mapped as upgrade options, you can upgrade to any of the available products by passing the specific product's Shopify variant ID in the variantShopifyId field.
• If variantShopifyId is not provided, the line will be upgraded to the first mapped product configured in the personalized upgrade profile.
• For a Product quantity + frequency change upgrade, use isMultiProductQuantityUpgrade and updatedProductInfo to specify the products and quantities to apply. Set isMultiProductQuantityUpgrade to true when upgrading to two or more products.

Multi-Line Subscription

• Only line items with an available SKU upgrade option can be upgraded.
• To upgrade a specific line item, pass its line ID in the sourceLineId field.
• If the upgrade profile has multiple products mapped as upgrade options, you can select the target product by passing its Shopify variant ID in the variantShopifyId field.
• If variantShopifyId is not provided, the line will be upgraded to the first mapped product configured in the personalized upgrade profile.