Make it illegal. Make it illegal for local advertisers to do business with them. Sanction individuals that cannot be locally prosecuted. Sanction the company.
It's already a requirement that to operate in Brazil they need local representation. Someone local who can be prosecuted, even if it's just a proxy - I'm hazy on the details but I remember reading about this at one point when they went after Twitter.
Is it going to fully stop Brazilians from using the service? Most likely not, but it will almost certainly reduce their usage, and the remaining users become a less profitable product to Meta, since they're not going to see ads for companies they can actually spend money on.
This changes incentives and may well be enough to make Meta rethink their policies. Or not, but then its effects can be measured and adjusted.
With adequate checks and balances, following laws approved by a democratically elected legislature, and when it's done to protect democracy and rule of law, then yes. If we can limit the reach of someone yelling "fire" in a crowded theater in order to cause a stampede and harming people, why not preventing the already yelled word from being heard by the crowd and cause the action to fail?
Not supporting the idea, but this feels like the traditional technical details vs practical real world solution.
Rather than banning individuals right to access a site, and then playing technical whackamole, you make that company's ability to operate in a country illegal. this puts the incentives and the technical onus where it belongs.
Again not saying they should or I support the notion of banning a site. Just that there are practical legislative solutions.