Maybe I can’t understand your difficulties because I don’t have any problems of this kind, but if you could give me some other examples of attacks that you have difficulty with, or even what your eyesight condition is.
This attack you’re talking about can’t be dodged by watching at the ground looking for the tentacles to see where they come from.
You have to watch the boss dig its arms into the ground and then keep walking until the attack ends.
The tentacles always sprout from under your feet, but as long as you’re moving, they won’t hit you (and they also appear at a constant rate so if you have a fast weapon you can attack between one tentacle and the other but with a slow weapon you should just go around the boss until it stops doing that attack).
This phenomenon is called “tunnel vision” and it’s something that happens to everyone. More vivid and flashy colors help a little but they’re not the solution.
With practice, you’ll become able to focus your attention on your surroundings even in isometric view. If this is your difficulty, the problem isn’t in the game’s animations.
For example, if you find yourself surrounded by even basic enemies (who have very readable attacks), if you’re not able to dynamically shift your attention, you’ll still find yourself in difficulty.
I don’t like these types of “markers” I find that they break the immersion, obviously it wouldn’t be a problem if they were an accessibility option that you could disable, but realistically I don’t expect the developers to implement them.
Honestly I misunderstood and thought you were colorblind, I expected you had trouble seeing the purple attacks that remain on the ground. It seems you haven’t encountered them yet. The fact is that, outside of these attacks, I don’t think there are any other examples of enemy attacks that you can spot based on their color contrast (the tentacles you had trouble with have a neutral color (and, as I’ve already explained, you avoid them by looking at the boss and walking, not by looking at the ground to see where they come from)).
So, a colorblind mode would probably help with these purple attacks that remain on the ground, but it wouldn’t be useful in your case since other attacks in the game don’t use colors to be visible.