Swipe down twice to the quick panel, then click the 3 dots in the top right and click 'edit buttons' then once you find 'secure folder' swipe it down to your desired place on the quick panel, then activate it, it should appear in your apps once you swipe up to see all apps, once you click it and set it up, click the 3 dots in the top right of the secure folder, and click 'add files' then choose images, then you may freely add your desired photos.
Right, so I checked, and since you don't have it set up you may need to find it in settings, so if you go to settings > Biometrics and security > Secure folder. It should work, if you cannot find it let me know!