Here are examples of the word/phrase "fearless" used in a sentence and paraphrased in a sentence...
Luffy is one of the most fearless, ambitious and determined protagonists in the history of shounen.
Luffy is one of the most valiant, ambitious and determined protagonists in the history of shounen.
He never backs down from a challenge because he is fearless.
He never backs down from a challenge because he is brave.
That hero is too fearless to ever be scared of any villain.
That hero is too stouthearted to ever be scared of any villain.
Other Examples...