Starting really with Demon's Souls back in 2009, the Souls-like genre was popularized primarily with the success of 2011's Dark Souls, a spiritual sequel that featured some of the most impressive puzzle-box level design and deep, deep lore that left tons up to interpretation.
While fairly niche at first, the genre grew in popularity, exploding with the massively ambitious and massively massive Open World take on the genre with FromSoft's Elden Ring in 2022. It's influential enough that other studios have either borrowed elements of the genre or just flat-out made their own that conform with basically all the defining traits of the genre.
The games have been a big influence outside of video games, and Critical Role's Matthew Mercer has cited the games as among his favorite. Daggerheart's Age of Umbra campaign frame was designed to try to capture the dark, apocalyptic feeling of these games.
But can a TTRPG really capture the vibes of a Souls-like?
I guess to approach that question, we need to define those vibes.
The gameplay mechanics of a Souls-like won't translate perfectly to a system like D&D. Ironically, the "anti-attrition" Draw Steel arguably has the best equivalent of the Souls-like healing system with its Recoveries.
Souls-likes are famed for their punishing difficulty, and while I do think that's a near-universal aspect of the games, I don't actually think it needs to be a defining one. What nearly every Souls-like game has, though, is an in-universe explanation for how you can keep playing after you die. The difficulty is basically accounted for within the game itself, and that means that your multiple attempts to get through a difficult section or boss are actually canonical.
In a strange way, this makes it more forgiving than D&D, where player character deaths can only be reversed using expensive magic (and, interestingly enough, banning resurrection has been a popular element in certain Actual Play campaigns, such as Critical Role's Campaign 4, as well as Dimension 20's A Crown of Candy (whose dire stakes and seriousness is part of the joke, because the PCs are all candy people in a world of people who are all some kind of food-person, basically Game of Thrones meets Candy Land).
How you want to approach this element of the game is open for debate: you might lean into TTRPGs' standard difficulties and make death rare, but then make it permanent. Alternatively, you might come up with a mechanic where death is frequent, but impermanent.
I think the latter is certainly more faithful to the genre, but you need to make death feel punishing in some way.
Ironically, Souls-likes make death punishing by actually making it less punishing that it would be in a traditional game. Here's what I mean:
In a classic video game, if you die halfway through a level (assuming there aren't checkpoints in that level,) you start over and all that progress us undone. In a Souls-like, the XP/Currency you've collected (which has a different name in most of its games, though it's Souls in Demon's Souls and the Dark Souls trilogy, so we'll call it that) is left near where you died. You have one chance to collect the dropped souls, but if you die on the way there, they're lost forever (I think Lies of P actually has you only lose part of them, and you can get upgrades to lose less). Even though this is arguably more forgiving, it creates a tension, because dying earlier in that level than you did previously carries a greater potential for loss.
Here's the thing, though: I don't think the kind of repetitive combat you have in Souls-likes works as well in D&D. When combat with an enemy or group of enemies might last four seconds, it's not that bad to have to fight something over and over again. But if your party needs to fight the same damned group of stone golems over and over, it's going to feel a bit tedious.
I will say that I think it could be fun to build a full game system inspired by Souls-likes, where there aren't strict classes, and instead you can build around certain stats and even certain mixes of stats (my best Elden Ring character is heavy on both Strength and Faith, for example, with weapons that scale with both).
But assuming we're using D&D as a system, I think we need to approach combat design, and adventure design in general, with D&D in mind.
That, then, leaves us the world building and tone.
I think this also offers a lot of challenges.
Again, I think you could build a Souls-like that doesn't work this way (I'm curious how One Crab's Treasure works, which seems tonally very different,) but generally, a Souls-like has the following story elements:
It's set in a world that has undergone some kind of apocalyptic catastrophe, with only bare vestiges of the civilizations that previously existed.
Our protagonist (and the player) is dropped into the world with very little in the way of context, given some vague mission whose significance isn't immediately clear.
Characters have very mysterious motivations, and use language and jargon that we need to piece together in order to glean the true meaning (and some of that stuff will never be fully explained. What the hell is Paleblood, anyway?)
There's barely any safety to be had - often we have some small hub where friendly NPCs gather after we find them in the world, but the degree to which those places are truly safe is debatable.
Most NPCs have side quests associated with them, which tend to end tragically.
They tend to have multiple endings, but the relative "goodness" or "badness" of those endings is deeply uncertain. (Though I'll certainly say I think the Lord of Frenzied Flame ending for Elden Ring is a bad ending, and I think Lies of P's Rise of P ending feels about as good as you could hope for).
Vagueness, though, needs to have something beneath it. While I'm not sure that FromSoft always has a strictly canonical interpretation for some of its story aspects (I'm half-convinced that they deliberately provide evidence for Marika and Radagon having originally been separate people and also evidence that Radagon was always an aspect of her, where there) I do think it's important that any weird details have some thought behind them.
This is, also, a very tricky thing to do in D&D, because unlike a video game protagonist who will only say things that are pre-programmed, if an NPC speaks in vague riddles, there's nothing preventing your players from, you know, asking follow-up questions.
One thing I think you can do is limit your cast of friendly NPCs to a small few. There aren't going to be multiple towns where you can buy weapons and armor; there's one friendly Blacksmith.
I actually think that a more sandbox-like approach could actually work quite well for the genre. This could let you place important progression materials in out-of-the-way places, so perhaps your Blacksmith NPC needs a magical grinding wheel of some sort to upgrade weapons to +1, which could motivate the players to travel to some "Altar of the Mining God" that is its own dungeon. (Rather than just dropping magic items, I might instead create upgrade materials that the players can collect.)
Another challenge here is that I think that a big part of the feel of a Souls-like is the sense of loneliness - though to be fair, that's not strictly the case all the time. Since Dark Souls at least (not sure if Demon's Souls did,) there have been online multiplayer elements to the games. Here, we must bow to the mechanics of D&D, which is built very much to be a co-op game.
Another adjustment I think you'll need to make is that D&D is a game where players should have multiple ways to deal with problems. In Bloodborne, you can't just talk to the wandering beast-hunters and explain to them that you're not a threat to them, no infected with the Curse of Beasts. But in D&D, there should be opportunities to resolve things outside of combat. This requires a more complex approach to quest design.
Primarily, I think the key here is tone - a surreal world, with lots of horror elements (particularly Dark Fantasy,) and a sense that defeating the villains is only half the challenge, while the other half is figuring out what, exactly, is going on, and what consequences our actions will have.