I've got a small issue what would you do? In my current job we got a new worker in but that new worker I know who he is. About 10 years ago he bullied me in my first ever job for having slight learning difficulties and threatened me, he didn't look at me once today hown should I deal with this

See how things plays out, before saying/doing anything.
It’s possible this person might feel ashamed of the way they treated you in the past and truly regret it & it might make them anxious to apologize or bring it up. 10 years is a long time & people are capable of growth/change. They may hope you don’t remember & would really like to see if you’ve forgotten & moved on. Dont harbor any hard feelings & maybe try with a fresh start. You dont know what that person was going through in the time of doing that and usually people that bully others have a pretty hard life & huge insecurities.
If this person threatens you again, you have the upper hand since their the new kid ya know? Also, if someone threatens you at work, that should be reported.