what hair dye does salons use ??

i know every place is different but when you ask for hair color do they do demi permanent or permanent? for instance if i used purple semi permanent hair dye and want it touched up and more demi permanent at the salon could they do that ? i’ve been wanting to find a good demi permanent purple dye and lighten my hair so it shows up more on my roots then semi but i am having a hard time finding a brand with good reviews so i may have to take a trip to the salon. thank you!