Top spec is like a natural based calmer sort of thing, it’s magnesium based and just takes some of the stress away
I got a smartpak supplement for my pony that really helps. I forget what it is called, but it is from smartpak. I also use a fly spray called calm coat that has essential oils to calm you down. It really works!!!
Magnesium is supposed to have a calming effect or just go to your local tack shop and ask what they recommend, there are various different calming supplements