I've been using a well-known password manager to create several identities for use on each web service I sign up to.
I had the idea of creating 3+ email addresses with strong passwords consisting of 40+ random characters and signing up on each service with a different alias, sometimes a word, sometimes random characters. I never supply my real data, only made up but realistic information. This way an adversary running OSINT wouldn't be able to cross-correlate a given identity attributed to me to another one on a different service, right?
I'm aware that by using the same computer and IP address to create and log in to all those IDs is less than optimal, but my concerns are purely those of privacy and I don't include nation-state level adversaries on my threat landscape.