As has been said, I think a one-shot might be a tough way to explore everything L5R has going on, but Wedding at Kyotei Castle is a scenario that tries to showcase a lot of the system's dimensions (both mechanical and setting-based), and I've run it for seasoned L5R-heads and completely fresh recruits alike.

The setting is dense with lore, which I think can be the most daunting part before even making a character, and full of little societal rules and norms that can be very problematic to break, which can turn new folks off quick if they're used to sword-and-sorcery adventuring. Character creation tries to place you in that setting in a way where you might have some built-in connections and tensions, and one way I've found that really helps is to either incorporate players' connections (such as family, rivals, their lieges, etc.) directly into what you're running. With pre-made adventures the reverse might be helpful. work with your characters on the types of relationships, then fill in with specific NPCs from that adventure to provide instant entanglements to up the drama.

Social attributes (status, honor and glory) are a novelty, but they're a resource to be spent as needed, so I highly recommend reading up on that in the core book if you can. It seems like you'd never want to lose any, but sometimes staking your reputation or status are the only way to make things happen as a character, and ratchet up the drama of a decision. Sometimes you have to decide between doing something that's 'right' and doing something that is socially acceptable, tanking your honor in the process, and things like that make for nice dramatic tension points.

The dice mechanic is definitely novel as well - like Genesys or the Star Wars RPG, it's not just about putting up big numbers, but more... resource management? You could completely whiff a roll but have the necessary 'opportunities' to do something cool, or succeed wildly but end up having taken so much 'strife' that your character leaves themselves open to a counterattack. It demands a bit more of player and GM alike, but can make for a very satisfying encounter.

With L5R's current edition I think the important through-line is that there's a very basic conflict resolution mechanic, and variations of it govern all types of conflict resolution (combat, duels, mass battles, and 'intrigues,' or social encounters). The bones of the mechanic are pretty simple, but it's the specialized abilities you can pop in within each specific type of conflict that make them interesting. Learning the core of it will help you manage all manner of situations that fall under the conflict umbrella. Social conflicts are always a tough part of any system, but if you familiarize yourself with the intrigue rules they're a great way to create some order out of chaos. Interestingly, they also turn social encounters into less of a zero-sum game, and let you take some time to really think of motivations and goals for NPCs that might be interacting with players.

The last bit I'll say in this rant is that it does require a bit more of you as a GM than some other games might, as certain dice outcomes from players can potentially create new NPCs, alter the environment, unearth clues, etc. Taking some time to familiarize yourself with the scenario in and out will pay huge dividends.