This is excessive.
Jahannum is like a rubbish heap and the people who are in the worst space of jahannum are trash - that is, those people who have no redeeming qualities and no hope of improvement because they have destroyed themselves. For instance, despots who wantonly rape, torture, and kill; or people who cheat the poor and live lavishly and show it off in their faces.
Allah mentions in the Qur'an those people whom He does not love (oppressors, etc), and from this list, we can get an idea of some of the biggest things that lead people deep into hell. Clothing style is not mentioned on this list.
However, one should remember, in the hereafter, our outer deeds are weighed along with our intention. So a person might do something that seems small in this world, but it would become big there because of their intention. So, for instance, if someone wears a certain clothing style with the goal to challenge or mock Allah and to spread a destructive ideology, this would be something very serious. Conversely, Allah might forgive a major sin like murder because He understands the circumstances.
So we cannot say 100% what are the results of our actions, but, in general, the worst parts of hell are for the people who do the worst things, like Firawn.
Some people say things like what you say based on some narrations which, when you dig into them, are rather questionable.
People focus on the outer more than the inner because it is apparent and because people have other challenges that relate to being a social being or controlling their own nafs, but Allah takes the whole picture into account.