I want to ask about diction. if I want to say "I am expected to succeed." can I say "I am slated to succeed?"

One is only Slated when it's a sure thing.
a lock

"expected" and "slated" do not mean the same thing. Stick with "expected".

expected and slated have two different connotations and should be used appropriately. To expect means to believe you will accomplish in time. To slate is to designate for a specific purpose. There you have it Say what you mean in your sentences. Remember this.To mean one thing and say another can be confusing. You don't want that, i assume. Good luck and much wisdom.