If I remember right Xianxia was supposed to mean something like immortal hero or something similar to that. A Chinese version of high fantasy and seeking immortality through various means, often with a large focus on personal enlightenment and understanding the universe, sometimes drawing influence or reference from classic Chinese folklore, history and myths like Taoism/Daoism, Confucianism, etc. Dao/Tao translating to path/way.
At least…in theory. In practice it’s often like the others have said-Chinese murderhobo MC wandering around chugging drugs like no tomorrow and pissing off everyone around them for no reason except they can, killing everyone who looks at them strangely (or who has some macguffin they want) and saying they’re King Dickhead of the entire universe and they’ll prove it even if they have to murder every last other person in existence (“ruthless” MCs)
Sects are a big thing as well-basically think of a gang/mafia of wizards/superheroes and all the conflict and political nonsense that would come with, complete with gang turf wars and all sorts of similar things. The sects usually basically boil down into rival gangs and warlords with their own personal turfs and they’ll fight anyone who insults them…or who they think insulted them….or has something they want to steal. Blood feuds and gang wars are frequent
“The man’s only sin/crime was being too weak to hold onto what he has” is something I’ve seen way more frequently than I should-basically might makes right and if someone wants to mug or murder someone else for some shiny thing they have, too bad, sucks to be them, their fault for being so weak. Except when it happens to someone they know, then it’s how dare the elder pick on the junior and they have no face and must be put to death for their crimes
Face/reputation is a big deal as well, and often there are (initially) non-violent clashes/scuffles the MC has with someone where he “slaps their face”, or publicly embarrasses/humiliates them (or they view it as being humiliation even if it wasn’t). This often leads to escalating violence that only ends when either the MC is dead or the entire enemy family/sect is wiped out.
You can also expect the “upper worlds” that often show up with the MC ascending to them to be basically the same thing but more people are immortal, yet somehow learn nothing and still act like psychotic murderhobos
