"This spray zhuzhes". What does "the zhuzh" mean in cosmetics?

She says: But this "zhuzhes" without effort or skill.

Zhuzh:

to make something more interesting or attractive by changing it slightly or adding something to it:

• The stylist said he would zhuzh up the outfit with a hat.

(Cambridge Dictionary)

Its origin is unclear and its spelling may also vary:

‘Jeuje,’ ‘Zhoosh,’ ‘Zhuzh’: A Word of Many Spellings, and Meanings: from nytimes.com

(I don't know if this will go down well, but I'll hazard a guess-etymology anyway — based on how is sounds and what it means.)

I'll bet that "Zhuzh" (or however it's supposed to be spelt) is directly related to:

je ne sais quoi | ˌʒə nə seɪ ˈkwɑː |
noun

a quality that cannot be described or named easily: that je ne sais quoi which makes a professional.

ORIGIN: French, literally ‘I do not know what’.

— Oxford Dictionary of English

The "almost everything cream" that Keira is talking about, apparently just make her hair better in a variety of somewhat vague/imprecise ways; it zhuzhes her hair up a little (it provides a certain je ne sais quoi).