By not using internet. No, seriously, if you access something over the internet, you will leave tracks. This here post is nothing new or inherently scary on its own. I used to have forum signatures that would tell people what browser they were using or from what IP they were coming.
What you really want to do is disable third party cookies on everything you own. That (and things like hsts super cookies) is what tracks you.
If you’re using an app to browse Lemmy, you might ask for their implementation to reject cookies and fingerprinting attempts when displaying images and other embeddables.
a minute later edit: And yeah, if you don’t like web services to know the IP address given to you by your ISP, VPN is a decent option.