there's many elements to this not really possible

a relay block list would be a good one, so you never send to relays you don't trust

the most important events that you don't want leaking are your app data and DMs, this is also about relays and their actual codebase and policies implemented therein

many relays just give those events out to whoever asks for them, it is a critical element of a functioning system IMO that at least relays make a decent effort to not leak your metadata events

the absolute level of invisibility to your enemies cannot be achieved without centralization, which means your enemy has a proxy to attack you with