Even though there are millions of different types of mites and most of them haven't even been named it is rare that we hear of mites on peafowl as causing problems. Most likely lice are the problem 'if' you have anything on your bird.
First a slight chastizing on buying birds at auction. Good, that's over. I have bought birds at auction too and brought home al kinds of problems. In the future you might want to find good breeders of peafowl and buy from them instead of getting culls at an auction.
There are three kinds of lice I can think of on peas, (birds in general), the ear lice, body lice, and feather lice.
Here are ear lice drinking from the eye.
Body lice look like these but are a larger and easier to see.
We use Ivermec pour on and give one ml per bird topically. A couple of drops on the back of the head for the ear lice, half between the shoulders on the skin, and the rest above the vent, gain on the skin.