Age has nothing to do with whether a character can be lumped into the "lol" category.
The only thing that matters is the character's apperance + possibly, in addition to the effect, the behavior itself. If a girl has a petite body, is very short and has girlish rather than feminine facial features, she can definitely be put in the "loli" category, especially if her behavior is rather childish and she's just cute. So she might as well be 24, even though some girls in real life look like that.
PS: And so, if a particular "work" describes her age, then even though she may not look that much in terms of the law that is what she has. And why? Because she is a fictional character and does not exist in real life.
PS2: Not counting extreme cases, of course. So why do some studios etc give up trying to release such more daring games in this aspect? "For the sake of sanity".
Yes, this is the preference of a petite, not tall girl with cute and sweet facial features and there is nothing wrong with that.
No one is making you download it or play it if it's so strongly restrictive in your environment.
Using Belgium as an example, here's a citation of their penal code:
"Is considered [CP]: Any work, image, video, or recital that features a person who is under the full age of 18, or a person whose visual appearance is that of someone who is under the full age of 18, or any realistic depiction of such a person."
There is no jurisdiction on what constitutes the term "realistic", so until a high court makes a decision, there's no security that loli stuff wouldn't be fall under this law.
As for "you can just not play it", yeah. You can. I dunno who is offended - I'm not - but that's not the point. The point is that if the tag isn't there/there's nothing that's properly hinting at the content being there, people could end up downloading something they weren't wanting to download.
Belgium is a very tame example, too. South Australia straight up bans loli stuff and has plenty of jurisdiction on the matter, as does France (although France uses the marker of "fictional stuff is illegal if they look under 14" which sounds even less enforceable.
Japan, meanwhile, follows the thing we all know; if you say she's 18, she's 18, 0 debate.
That being said, I don't know why people get offended at the notion of adding a loli tag to characters who look like loli's. It's not like this site filters it or bans the content, it's just choosing visual tagging over "lore-based tagging" if you will; which is the reason "legal loli" is a tag on a lot of sites to begin with.