Maybe I am too old, but frankly, I do not give a damn for any distinction for the demographic of the 13-17yo. You have to be 13yo to use itch per tos. So the only important age restriction is adult yes or no.
Since there is no curator system and no user tags that I would know of, all games that would have to be restricted by their content and not by their age appropriateness, would be dependent on the rating of the dev. And those would be ... questionable.
For adults that look for games to play with their children, there do be tags. If it is tagged horror, for kids it ain't. And if the dev of a jump scare game would not tag horror or similar, that dev surely would not have rated it correctly for any maturity preference.