If I want to say I am wrong, can I say " I am off course"
If I want to say I am correct, can I say " I am on course"
I don't recommend using this expression as a synonym for "I'm right" or "I'm wrong". However, it's possible as a figure of speech. The context would have to justify it somehow.
figure of speech: An expression that uses language in a nonliteral way
Form of expression used to convey meaning or heighten effect, often by comparing or identifying one thing with another that has a meaning or connotation familiar to the reader or listener.
I agree with PROESL.
The expression "on course" or "off course" strongly suggests TRAVEL, or PROGRESS.
That means that "on course" is not a good synonym for "being correct."
Instead, it can be used as a metaphor for "heading in the right direction" or "staying on the right path."
> The high school student dreamed of going to college, so he stayed on course all through his senior year. He didn't get in trouble, and he studied hard to get good grades.
> When he was accepted to Yale, he thought, "I was right to stay on course. I was correct when I decided that staying on course would be the best thing to do."