You can do it using Bixby Vision on your phone (if its after the s7 series)
OR
If your Galaxy device doesn't support Bixby Vision, you are still able to scan QR Codes however this will be directly through Samsung Internet or Samsung Internet (Beta). Usually the Samsung Internet application is pre-installed on later Galaxy devices however if you have uninstalled this app or you are unable to locate this app within your apps tray, you can easily download it from the Google PlayStore.
Samsung Internet makes separate QR code reader apps totally irrelevant. Samsung's browser includes a QR code reader directly in-app, which makes scanning website QR codes a breeze. Just enable "QR code reader" in the Extensions menu, then tap the three dots to access "Scan QR Code" at any time.
You will need to enable the QR code scanner from the extensions of the internet browser.