No, its full on RNG. The game even admits this by straight up telling the player various mechanics are luck based. Take Mukuro for example, sometimes she just does her basic lust attacks which dont inflict any statuses and you can beat her pretty easily by just attacking with lightning or whatever.
Other times however, all her attacks will successfully inflict their statuses, sometimes re-afflicting you with the same status you just removed. She will then bind you every turn, requiring you to struggle out repeatedly while draining your Vitality, which you will need in order to remove ecstasy and puppet so that you can actually attack her. She inflicts two sets of ecstasy on you? You better get rid of that shit quick, but then she ends up binding you again and you get hit with a third stack on the next turn and its a RIP.
Sometimes she will use a bind move while you are still in a bind, one of which is a instant kill if you dont struggle out of it. But get this, sometimes struggling doesnt even let you escape the bind, resulting in a game over. and then to top it all off, if you finally manage to get your willpower and vit in a decent place and have a good window to attack... your attacks can still miss... yeah, seems to me like there is quite a bit of RNG.
Disclaimer: This is my opinion and personal experience with the game, you are entitled to your own thoughts and are equally valid or even more plausible then what I say below.
Let's tackle these shall we? Concerning status effects, items and Cool Calm are your absolute friends, guides will tell you that late game, you're going to want Cool Calm for it's utility in defeating the later enemies.
Mukuro of course has two types of binds, the usual bind and her special bind. Her normal bind isn't as difficult and even the wind magic you start with will get you out of almost any bind. Her special bind is warranted by glowing red eyes and a text prompt, since it's impossible to move in stopped time, you have to use defensive stance to reduce the damage significantly.
While Rng is prevalent to a degree, the game is difficult due to having to master different mechanics unique to each demon, it still sucks when an enemy lands a bind on you. I can understand if you were just talking about the Daji fight, which sucks because that was pure RNG when it came to the Beast Form.
At the end of the day, skill isn't where this game relies on but by utilizing the mechanics in your favor(and admittedly some luck), the game was made in way to make you suffer defeat at every turn, the protagonist is only a human against man-eating demons, you're supposed to lose (at leas tin terms of the story describing demons).
Status effects? Cool Calm, Bandages, Morphine, Vitamins and Rations will prevent most effects from happening.
Binds? Wind Magic will get you out of most bindings, Slyph Storm will allow you to dodge most attacks.
Lust? Never let it reach over 50, you need to utilize every opening you have to recover, Vitality can hit zero but lust can't.
The only thing that really sucks is how the corruption system works, seriously screws you over. At the end of the day, RNG does play some part in battles but knowing how the game works is crucial to winning. Except EX dungeons, all strategy went out the window for that one in my opinion.
Either way hope you have an amazing day and stay safe! Remember this game is unfair for story purposes and so you should always start on the easiest difficulty and don't be afraid to go through multiple runs and get assistance, you can always do True Mercy next time.
Till next time.