You could have just Googled this if you just wanted an answer...

If anyone doesn't want to give Reddit any kind of traffic, the answer is this:

There have been studies done on dead transgender people that demonstrate that trans people have differing brain structures; a trans woman's brain will have many (but not all) of the features that a cisgender woman's brain has. The same goes for trans men.

source: https://brain.oxfordjournals.org/content/131/12/3132.full

There is no such evidence for transracial people as that's not really a thing. Race is much more of an artificial concept than gender, and has little biological basis. Black people are not of a different race than white people, they simply have different genetic traits that are well within the boundary for counting as the same species.

race as a social construct: http://www.jstor.org/stable/188702?seq=1#page_scan_tab_contents

Brain regions can be considered masculinized or feminized depending on their response to sex hormones (look up the preoptic area for a well-studied example of this); there's no such thing as a 'race hormone' that can 'blacken' or 'whiten' brain regions.

estrogen modulates neuronal movements within the developing preoptic area/anterior hypothalamus: https://pmc.ncbi.nlm.nih.gov/articles/PMC2295210/