Your brother is on a (specifically designed and heavily funded) pipeline to being a total piece of shit (not just with misogyny, but racism, and probably queerphobia and ableism too), do what you can to get him off it. A quick search brings up what looks to be some good info to start you off:

Manosphere

Misogynistic influencers are trending right now. Defusing their message is a complex task

De-radicalising incels out of the ‘manosphere’ through Reddit

Making a Radical Misogynist: How Online Social Engagement with the Manosphere Influences Traits of Radicalization

Swallowing and spitting out the red pill: young men, vulnerability, and radicalization pathways in the manosphere

Exiting the Manosphere

There are also many youtube videos on the subject, though I haven't watched any recently, so I won't link, but look up something along the lines of "manosphere right wing pipeline" and you should see some results.

[–] masquenox 1 points 1 hour ago

Fucking hell, I had to scroll all the way down here to find an answer that isn't complete garbage.

[–] jordanlund 33 points 16 hours ago

The Alt-Right Playbook videos are an also must watch, starting here:

https://youtu.be/P55t6eryY3g