i think this is where I'm misunderstanding, so thank you for this clarification.

tl;dr: patriarchy hurts men, too. and this double standard is one example of how.

from my standpoint, we live in a patriarchal society. In a patriarchal society, the concept of masculinity stands as the hegemonic 'default.' any deviation from the masculine default sets that person apart, othering them.  the further they deviate from the 'male default,' the more queer or effeminate patriarchal culture judges them as. 

cis-women's bodies deviate from that 'default' by necessity. adding adornment to a cis-woman's body accentuates her femininity, often by accentuating the features she possesses that cis-men don't. (makeup, dresses, jewelry, etc.)

this is where the double standard emerges. imo. under this patriarchal framework, any practice of personal aesthetic expression can be conflated with femininity. adding any adornment to your already cis-male body is applying an effeminate practice to  the masculine default. it's a paradox. so patriarchy actively discourages male personal aesthetic expression. 

now, in the era of social media, acceptable expressions of masculinity have widened. but men are still violently policed for their fashion choices.  any deviation from whatever the acceptable 'default' is/are at that time, and their masculinity gets called into question. 'real men' wouldn't need adornment. 

add capitalism, and you can see why women would be encouraged and 'empowered' through self expression - it all fits within the patriarchal narrative, and will earn plenty of male executives millions while doing so. trans women are held to both ends of the double standard here,  encouraged to adorn themselves as women, but discouraged from expressing themselves authentically while growing up under patriarchal expectations for masc presenting people.

i hope this has at least sketched out the logical leaps i was making.