With Shopify, you can use a discount (coupon) promotion URL to offer discounted sales to visitors who come from a specific page (such as an influencer account), but this is an example of how to set it up if you want to run a campaign that automatically gives away products instead of offering a discount.
Example of setting up a gift when purchasing from a specific source
[Method 1] Add a customized Liquid section to the header group and insert code that sets the from parameter to the cart attributes.
[Setup Method 2] Create a Flow that adds a product to an order when specified values are set in the cart attributes.
