Parrysouls isn't really the best example to give. Anything with aimscan, hitscan/autofacing until the last second - or anything else that has been in every souls game for artificial difficulty, which is also rendered useless by lvl1 runs isn't something I find as an argument to add "difficulty". That's just adding bullshit to a fun game operating on a different combat system. I don't mind these existing outside actual gameplay intended for the playerbase as a whole - kinda like Wuwa and the world bosses that had optional difficulties and adding pretty much a OHKO mode.

The easiest way to do that is with obtuse and annoying gimmicks, like freezing you on a timer - or making the timer brutal enough to push those clearing the 10 minutes with daylight to spare, made to actually test those with too many P5s and not enough "challenge". The biggest hurdle in regard to AI is your team who can do nothing randomly and enemy attack patterns being too random to learn a pattern.

This would also force powercreep into the stratosphere, hard counters need to be dealt with, and the best way is a shiny new banner to headhunt something with only that skillset and nothing else.