If you are referring to the precision from dex, yes, that is in his kit to gain 1 for every dex and use one per hit.
It that isnt what you are referring to (and even if you are) maybe try words in the post instead of a series of question marks so we aren't guessing what your question is
Are 12 pure (yellow) precision buff all at once possible which are not yet corrupted part of Vox kit?
Its in his kit. You can stack yellow precision dex buff as much as you like.
Here's the line from his abilities:
"The Precision Buffs granted by the Dexterity Mastery have no stack limit, and fall off one at a time with each of Vox's attacks"
So, there's no stack limit when the Precision Buffs are from the Dexterity Mastery, even while you have Corrupted Precision. Once you land hits, they become Corrupted and the max stack limit for those Precisions is 10. You can keep building normal Precision even while you're at the max stack limit for Corrupted Precision as well but you won't get any more Corrupted Precision when landing hits.
Thanks
it’s honestly a useful counter when we have a double track objective Can’t Touch this; wait until you have a stack of 15. o)