Wo Long: Fallen Dynasty won't feature difficulty options like Team Ninja's more recent Stranger of Paradise: Final Fantasy Origin, instead taking notes from its previous work on Nioh and its Souls inspirations.
"We're thinking it's 'good' to have one set difficulty so that everyone has the same experience of overcoming a really intense obstacle and they all have that feeling of achievement, like I did it," producer Masaaki Yamagiwa said in an interview with MP1st. "Wo Long is not an easy game by any means but we're working to give players as much freedom and agency to play it as they want, overcome obstacles in their own way."
Yamagiwa goes on to mention a new morale system that makes you stronger the more you increase it. But you can also "level up your character like a traditional action RPG", so it sounds a little like Demon's Souls' World Tendency, though it remains to be seen in action. And if you're struggling, there's multiplayer, so you can summon up to two people to help you take on bosses.
Team Ninja has been moving back to the one-difficulty-fits-all model of Nioh slowly with Stranger of Paradise: Final Fantasy Origin's DLC which is only available on the highest difficulty. For those who played through the game on easier options, this is no doubt a huge spike that might even wall off completion, but it has paved the way for Wo Long: Fallen Dynasty's more Souls-like approach.
The difficulty doesn't stop there either as Wo Long: Fallen Dynasty is taking a note directly from Dark Souls 2 and Demon's Souls with enemies that can summon real players to help them out. When you run into these lot, you'll have to contend with invaders as well if you're unlucky, which could go one of two ways - you end up fighting someone who can barely hold a stick, making for an easy win, or you get an experienced Souls-like player who you stand no chance against. When in doubt, run.