I see so many horror games but don't know a tag I should use and I just want to search threw games but there's just so many horror games
Please see the countless topics made about it, one pinned at the top of this category, another on the first page right now. Or this old topic.
There are also genres on the left side of browse to select. I would assume not much horror in racing and sports games. But after you found games you like, you will see what tags are used there. You should know at least a little bit what type of game you search for. Tags can be anything. Even banana is a tag.
There are sections linked on itch.io homepage directly, like fresh and featured. There is also the top-rated subsection of the browse section. https://itch.io/games/top-rated
And hidden on the bottom of the homepage is also this, if you have no clue what to play. https://itch.io/randomizer
But if you go to popular ranking, well, horror is popular, you get what you browsed for.