Game designers should just avoid putting difficulty modes because they can't do them. It's also relative.

You know what the old FF games did?
ATB speed and Active/Wait. Those were your options.
Too fast? Slow it down and/or put Wait mode on.

BAM! Difficulty changed! https://twitter.com/Kotaku/status/1248600376334602243

Those were like difficulty and accessibility options rolled into one, albeit on a minor scale.

It's 2020 [current year argument] so why can't we just have better customization than back in the 90's?

Just focus on accessibility.
Many games are lacking in that department.

Subtitles: have them, and let me change the size.
Color picker for your visual indicators and UI.
Saturation differences, that one color text is hard to read.

Accessibility options can serve as difficulty options.
Visual indicators and menu time stop: OFF.

"Hard Mode" says nothing.
If it means I have to play HP bar ping-pong more often or longer, just don't bother.

Just hand the difficulty changes to me - the player.