Well, I can't write a ton for now, but I can tell you guys how to dye your wigs, if they're synthetic hairs
First, make sure you have one that is heat-resistant. If you have human, or some other organic hair (there have been wigs made of like, goat hair and shit), this isn't necessary, honestly. Also, it can only be dyed darker, so start with a white, silver, or blonde color
Get some fabric dye. I use RIT because it's readily available, and it has a very
handy color guide on its website to get the exact color you want
Get a pot that won't be used for food in the future, and put in the appropriate amount of water and RIT dye, and bring it to a simmer. Wet the wig a bit beforehand (not drenched, though), and carefully submerge. The longer you put it in, the darker and more intense the color. If ombre is your desired look, it's easy to do, actually. Just place the part you want darkest in first, and slowly submerge. It's important to test out your colors on a similar piece of synthetic hair, first, so that you don't ruin a perfectly nice wig
This is how I did it, at least. Though supposedly you have use the RIT dye in the same way you'd use regular hair dye, i.e. applying it with those brush things. I haven't tried it yet, but
I'll link to it here, and when I have some time I'll check it out to see which is more effective, if you'd like me to