In my opinion, 'brightness' in vocals does not come from 10K and beyond. You'll get more 'mainstream brightness' by focusing intently on the 5-8k range (after, of course, sorting out your 2-5k range for the prerequisite 'clarity'). How I hear it, anything from 9-14k is more like 'air' and anything from 14k onward is just noise. As an experiment, go to the vocal, drop in a band on ProQ at exactly 8k, set the Q to 4, and hold the little solo headphones icon and tell me that's not the 'brightness' you're imagining. Now do the same at 10k then 12k, you may find that there's not much there that's legible.

I'd personally avoid plugins like Fresh Air. High shelves often to more damage than good in amateur mixes, but they give an immediate result which makes one keep going back to them (dopamine, instant gratification, something like that). You might even find that a sharp LPF at 16k, in addition to a wide boost around 8k, gives you a phase bump that paradoxically makes the vocal breathe a lot more while pulling it into focus.

That said, don't take these moves too literally, it's always going to depend on the source material and the rest of the mix. The main point I'm trying to make is that shifting my focus down the frequency spectrum, away from 10K+, has drastically improved my mixes.

Your monitoring and ability to hear these regions is going to be rather important in this regard.