The question of difficulty came to mind while playing Metaphor. It was pretty challenging early on when resources were very limited and I was also learning the gameplay systems, but I'm starting to feel powerful now mid-game (while still being challenged a bit). That's where I like to end up, typically. It has a nice ludonarrative feel for the games that typically have you killing god.
What do you like?
Difficulty curves are exceptionally difficult in turn based RPG games.
If the game is too easy, you have essentially designed a game that requires the use of very few mechanics and thus lacks depth or replay-ability. Fewer options to choose from essentially makes an easier game to balance the difficulty, but you remove player agency. A good example of this (and I mean good) is Final Fantasy X which has player agency in the form of the sphere grid, but the system is mostly linear until the late game and the mechanics basically force you to use the right character against the correct enemy for the first 10 hours or so of the game. This is good design because it forces the player to engage with the systems that exist in the game but gives them very few options to shoot themselves in the foot.
Conversely, if you want a more open player-agency design, I would recommend looking at the balance difficulty of Final Fantasy V with some notable asterices. This game gives a lot of player agency in terms of team composition and stat allocation (in a round-about way) but this comes with the down side that most encounters have to be designed punishing to certain playstyles to encourage changing your party configuration. While grinding in most games feels like a chore, FFV actually adds achievable "goals" in either mastering jobs or unlocking more job abilities, which basically increases your character's overall flexibility. The downside is that bosses can be brick walls so a pseudo-fail state (as in, keep progression but respawn in the last inn) would be a nice patch that would make the game easier for new players. Additionally, systems like the 4 job fiesta would be nice as a "hard mode", if a game were ever to ape that design.
Both of those designs work for me, personally, as long as the game is upfront about it's design decision and that the difficulty scales appropriately to the number of choices I have (This means the game has to essentially become easier, because permutations dictate that my team composition might be radically different from someone else, or there need to be mechanics that help make "catching up" faster like FFV/Bravely Default)
One thing I appreciate about FF5 is it allows for more of that flexibility. Fewer bosses like FF3's Garuda or dungeons like Cave of Shadows that will give the player a particularly hard time if they don't follow the prescribed party composition.
I was mildly concerned, as Metaphor had a little bit more of this than I liked at first. It seems to be easing up on this as the game goes on with more flexible options made available, fortunately.