What is an immediate turn on when you first meet someone?
Brains. My partner is someone I met on a MUD (essentially text based RPG) who had a character that my character arched and we constantly schemed against each other - until we started scheming with each other against the world.
When they have some of the same interests as you, but for different reasons. It provides for excellent conversation when you can talk about something you’re both passionate about, but because you’re passionate for different reasons, you have different perspectives, and it keeps a topic you’re very familiar with very interesting.
Emotional intelligence.
An unprovoked smile
This is the perfect example of “things physically attractive people can do to strangers without negative consequences.”
Edit: in retrospect, I think this statement is true for people that are intentionally meeting each other (as long as they don’t smile unprovoked too much, attractive or not).