Advice about dyeing over my highlights

My hair is jet black and I had subtle highlights done about a year and a half ago.

They've now gone a bit orange and have grown out quite a bit and I was thinking of dyeing over them with another colour like burgundy/purple. If I just stick it over all my hair will only the highlights pick up the colour since my hair is so dark?

Or is this a really bad idea? I do quite like the effect of the orange too, it looks like toned down ombre. Don't know if this is a bad idea.

Also I've never dyed my own hair before what's a good dye to use?

Thanks for help