Sometimes a character might refer to themselves as an adult who hasn't grown in yet, such as finley_(tloz); or others who are referred to as an adult by others, like tulin_(tloz), who gets called an adult by Harth and Teba early on in their TotK storyline (despite shortly beforehand being called a hatchling due to his personality).
These are both vague statements, so I can certainly see a focus on the body shape, and many people would blacklist (or search) based on that, but I'm curious if vague-er statements should apply.
Tulin in particular has an obvious age-up between Breath of the Wild where he looked like a child, and Tears of the Kingdom where he looks like a teenager, so even if his canon design and size can get the lore tag, any image using that design but looking like a child (such as post 5907241) should not have the lore tag unless the artist says so.