This is the most common gray area. You cannot see photos they uploaded, but you can see photos other people uploaded that tag them.

Even if User A has a locked-down profile, User B (their friend) might have public albums. When User B tags User A, that photo becomes visible to you—unless User A manually removes the tag from their profile.

How to view tagged photos:

Limitation: Facebook allows users to review tags before they appear on their timeline. Most privacy-conscious users have "Timeline Review" enabled, meaning they hide tagged photos from their profile immediately. If they have done this, you will see a blank grid.

Any website, app, or method claiming to let you "view private Facebook photos" is:

Facebook has a feature called "Mutual Friends Visibility." If you have 20 mutual friends, you might see photos that those mutual friends have interacted with or commented on.

Even without friendship, if they have any public photos, the Photos tab will be visible (though greyed out options will appear). Click it.

This works only if the person has made their content public.