Of course it should be high leg socks. Leggings are not a good choice, they are too hot and not free.
Not all thigh high socks could cover the tattoos. It should be longer thigh high socks. It must be able to cover almost the entire thigh. If the tattoo is on the middle of the thigh, then the thigh high socks must be long enough and cannot slide down, and they should be able to stay on the thigh all day.
Black or dark-colored thigh high socks may be better. Obviously, black is the best choice when it comes to covering tattoos. White or other colors may also be possible, but black will be the safest choice, and black is also more lovely and more mysterious, isn't it?
It is very important that the thigh high socks must be thick. Even if they are all black thigh high socks, they are completely different. Some thin thigh high socks look normal when you just open them, but when you wear them, after they are stretched, they will start to become transparent or semi-black, maybe they also great, but it can't help you cover your tattoo. Thick thigh high socks remain mysterious after being stretched, without losing the density of color, they will perform better.