If you know who you are and what you believe in then you should have no fear like others are saying. Go wherever you want and talk to whoever you want. I used to regularly post on /r/debatefascism before it got banned on reddit. I was disappointed when it got banned.
When you argue with someone online, you'll never change their opinion.. but you may sway some random lurker just browsing through.
I understand that a lot of the far right use "free speech" as essentially a dog whistle- but freedom of expression in my opinion is a vital part of a free society. That doesn't mean private places like Lemmy instances have any obligation to follow free speech. But I do support and respect places that do.