Reasons Your RP Characters Might Look Like Edgy Tryhards

They run around armed with weapons that look like mall ninja fare. IE, the kind of impractical weaponry talked about here and here, or the kind of stuff you see on this subreddit.

They carry weapons around even when they probably don't need them. Unless they're deliberately supposed to look irrational/paranoid doing this, this just screams "trying too hard!" all over.

They flaunt their weapons or powers in front of others. For example, by twirling their guns or knives, or by making fireballs if they have fire powers, etc. This can make them look like they're just trying to show off how dangerous they can potentially be.

They wear clothes and whatnot stereotypically associated with a "badass" or dangerous image. EG, conspicuous amounts of black, leather, or metal; conspicuous mystical/occult symbols, hoods, pseudo-Medieval gear, etc. (And no, black and leather are not good for stealth.)

They spend a lot of time lurking in shadows, dark corners, trees, rafters, etc. This usually happens because the players are trying too hard to make their characters look mysterious or foreboding.

They often bring up topics that most people would find shocking or uncomfortable. People often do this to try to make themselves look tough by showing off how unaffected they are and/or because watching others get uncomfortable amuses them or makes them feel superior.

They glorify or romanticize things most people consider harmful, negative, or evil. People who do this kind of thing are very often just bored and looking for attention or amusement, so characters who do this run a risk of coming off this way.

They frequently mention that they don't care about topics that others care strongly about, or that they think others would expect them to care about. If they're constantly talking about how they just don't care about this or that, they're probably trying too hard. Same goes if have to go out of their way to establish their apathy to others - such as by inserting themselves into conversations they weren't part of in the first place, or bringing it up when it's not directly related to the topic at hand.

They share their revenge fantasies. Perhaps they gleefully talk about how if it was up to them, they'd just wipe out everybody. Perhaps they go on in lurid detail over what they'd like to do to those they consider to be awful people, or what they think these awful people deserve. Or perhaps it's something else. However they do it, it can come off as childish posturing. (Or worse, they might make themselves look like future despots, serial killers, or mass murderers.)

They often state rightitudes. A "rightitude" being a belief or view their associates share and hold firmly - to the point where for them, to say it is to state the obvious. For example, if someone states that someone was brutally murdered, a tryhard will immediately launch into a tirade over how wrong murder is and how unthinkable it is to do anything so horrible to anyone else. Since the associate already knows this, and the tryhard knows the associate knows this, the tryhard comes off as trying way too hard to look like someone passionately concerned with justice and being good.

They frequently talk about how others can't understand them, or about how others are frightened by them. This can indicate that they're trying to cultivate a "too hot for you to handle" image.

They brag about "tough" things they did (or allegedly did). They make a point of talking about this stuff, particularly when it's not really relevant to anything and/or when nobody actually asked. (Quick tip - anyone who can easily and casually perform some tough or gritty action probably isn't going to find it particularly worth talking about later, unless it's actually necessary to mention.)

They often talk up how difficult or dangerous challenges or crises they faced were, or how tough/gritty they had to be to overcome them. Rather than just, say, simply recounting the facts of what happened and how it happened and leaving it at that.

They have to one-up challenges or crises that others have faced. If anyone else mentions having gone through or accomplished something difficult or unpleasant, they have to bring up and talk about when they faced something worse and/or bigger.

They talk as if every getting through every crisis is all about being tough/gritty. And overlook other potentially-necessary skills such as cooperation, diplomacy, patience, creativity, long-term planning and strategizing, healthy coping strategies, etc.

They spend more time talking about how you've got to be tough/gritty to get through a crisis than actually teaching the practical skills necessary to get through it. This can indicate that they're more concerned with maintaining a strong and tough image than actually making sure that others know how to be strong and tough themselves.

They spend more time talking about how scary or terrifying something is than actually teaching people how to handle the fear when facing it. Same as the above - they're probably more concerned with looking brave than actually making sure others know how to be brave themselves.

They speak of others as collectively being inferior or pathetic. For example, they talk about how "humans are so foolish" or refer to the everyday problems and concerns regular people face as "petty affairs."

They insult or denigrate those who aren't as edgy as they are (or want others to think they are). For example, they insult those who prefer Disney's versions of fairytales over darker versions of them (or just insult the Disney fairytales themselves), or they accuse people of being chickens if they don't want to listen to some gruesome tale of gory horror, or they claim that anyone who doesn't want to do some extremely painful and unpleasant thing are cowards. (Bonus points if they've never actually done it themselves and/or will never have to!)

They talk as if the more danger and/or pain something involves, the better it is. As discussed here and here, this isn't necessarily true. Those who talk like it is probably don't actually know what they're talking about and might just be trying to sound tough/gritty.

They emulate people whom they consider badass. They don't merely try to learn the skills that they think make these people so badass or try to imitate the traits that potentially make them good people, but they also adopt their personal tastes and preferences, their fashion styles, their mannerisms, possibly even their whole worldviews, and sometimes even their flaws.