like in dg some mobs are more important is there anyway to change color or anything about some mobs?

I totally 3rd this! However, I will try your method here first.

I always vote KUI but really wish it had capability to change colors. For example I think Explosives are much easier to spot when a different color. Or the best Schism target per pull in M+ standing out with a color. Or even debuff tracking..... Happy to support any way I can

There is https://www.curseforge.com/wow/addons/kuinameplates-target-helper as well now

Edit, also looks like when you change the color of a unit it fails to interact with the execute rage feature.

Second this, would be nice if you could expand KuiSpellList to associate npc ids with color for default health. NPC IDs can be parsed from GUIDs

This custom script can change the bar colour of the mobs named in the table: https://github.com/kesava-wow/kuinameplates-customs/blob/master/custom.name-and-target-colour.lua

As an example, by default it makes "Meredil Glider" pure red (r,g,b = 1,0,0) and "Fel Explosives"... purple? (r,g,b = 1,0,1). You can just change those names/numbers, as long as you don't remove any quote marks, etc.

I realise it's not the most user-friendly, but customs are where I put this sort of extensive customisation, until I either come up with a nice way of integrating it, or enough people ask for it.