I recommend just having as few accounts as possible, and typically only staying logged in while it’s necessary (i.e. by deleting cookies when you’re done), and using Tor in situations where it’s important to hide your identity. (There’s a lot more to think about, but it’s a good start)

For YouTube, there’s Invidious (example) and Piped (example). For Twitter, there’s Nitter (example). There’s a list of these services here