Retargeting
Retargeting (remarketing) is a method of showing ads again, on other sites and on social media, to users who once visited a website but did not go on to purchase or sign up. During the visit, users are identified with cookies or pixel tags and tracked through ad networks. The experience of "an ad for a product you looked at once appearing on a different site" is retargeting.
Combining QR codes with retargeting makes up for a weakness of offline advertising. A user who scans the QR code on a flyer or poster and visits the landing page becomes a retargeting target at that moment. This makes possible a flow in which a user who scanned a QR code in a store but did not buy is shown the same product in a social media ad at a later date to encourage the purchase.
However, with cookie regulations becoming stricter, retargeting based on third-party cookies is declining. As an alternative, a recommended design is to encourage visitors to register an email address or add the account as a LINE friend on the QR code landing page, and to shift to retargeting based on first-party data. If you design the CTA of the QR code along the lines of "10% OFF when you sign up for the newsletter," you can build a foundation for approaching users again without relying on cookies.