Change the hair according to the outfit

@lunebleue642, do you have the Mod that that post was referring to?  The only way you can change hair color with each outfit is with a Mod , either that one or a similar one. (If you play on a console  like PS4 or Xbox, then you can't use Mods as of this time).  
But if you play on a PC or Mac then you can use Mods.

If you don't want to use Mods or if you can't use them, then your only options are to use the few hairstyles that have color variant options.  There are only a few in the base game, but depending on which packs you have you might have more. 

Here are some examples:
Base Game regular hair color:

Base Game color variant of same style above:


Another base game color variant:


A color variant from the Get Famous EP:

A color variant from the Island Living EP:


Some of these hairstyles have regular counterparts but some don't.  I didn't show them all.  These types of hairstyles are your only options for changing your hair color with each outfit if you don't want to use Mods. 😇

Edit to add: Your English is very good! 🙌 Certainly better than my very rusty French! 😃

@lunebleue642 If you created CC hair using Sims 4 Studio and it is not properly showing up in your game you can also ask for help at the Sims 4 Studio site. There are many tutorials there and a chat board where you could ask questions. Creating custom recolors of the same hairstyle mesh should allow you to do what you want and have different hair colors for different outfits.

@PugLove888 thank you for the answer.

I'm playing on PC, but I don't understand what Mods you are talking about ?

@RandomBuzziness thank you for your advice.

I'll search some answers there.

@lunebleue642, I'm sorry!  I was confused because the link you gave had the topic of finding a Mod that lets you change the hair color per outfit category, and then the solution is to use Sims 4 Studio which is a tool for people who make Mods and Custom Content (CC).  So I thought you were referring to a Mod, since that was the title to the link you gave. 😳  I'm sorry for the confusion. 🙂 Thank you for replyng! 😉