One great thing about Lemmy, you can always start your own instance. However, I strongly suspect that you will quickly find your instance defederated from just about every major instance. The thing is, that "free speech" doesn't mean other people have to put up with anything you say. It does mean that you are free to go about saying whatever you want and are free from prior Government restraint on your speech. That isn't completely without limits however, making specific or terroristic threats have generally been ruled to not be protected speech. You can also be held accountable, after the fact, for the effects of your speech.

For example, you are free to yell "fire" in a crowded theater, no matter how many people incorrectly state otherwise. And, in fact, if there is a fire in said theater, you really should. However, if you yell "fire" in a crowded theater, with the intention to cause panic, and that panic results in injury or death, you will be held accountable for your negligence. It's not the speech which is illegal, it's the negligence. Government limitation on speech has to be very narrow and have a vary good reason for doing so. That's a high bar which many laws have failed to meet.

All that is to say, "free speech" is about Government action, not private action. Once you are on my property, I don't have to tolerate your speech. If you show up on my front lawn and start screaming "I hate puppies!", it's my right to tell you to get the fuck off my property. And, the police will assist me in enforcing that right. Though, at that point the issue is trespass and not your speech. There is some limiting of my property rights when I am operating as a commercial entity; but, telling someone to leave, because I don't like what they are saying, is not among those limitations. Technically, I could run a store front and tell anyone to leave who states "Nazi's are bad". Yes, they are objectively right, but it's my property and I can restrict speech on my property in that way. The same logic applies to online forums.

That brings us around to your request and later response to someone asking about the limitations you dislike:

Doesn’t seem true, most instances have a long list or rules and doesn’t seem to tolerate basic slurs

So ya, that's not a "free speech" issue. The Government isn't doing anything to you. It's just that no one wants to be around you. You've decided to act in a way which many of the major Lemmy instance owners don't want on their servers. And it's their right to tell you to leave. Maybe, instead of looking for a Lemmy instance to support your anti-social behavior, take some time to reflect on why it seems that you are being isolated. As the old saw goes:

If everyone around you seems to be an asshole, try looking in a mirror.