You could, however, try these options:
* Use the phonetic spelling: "Jarrett" could be spelled "Jarret" in French, which sounds similar.
* Translate the meaning: If you know the meaning of the name Jarrett (like "strong warrior," "gift of God," etc.), you could try to find a French name with a similar meaning.
* Choose a similar-sounding name: You could choose a French name that sounds similar to "Jarrett," like "Jared" or "Jérémie."
Ultimately, the best way to translate "Jarrett" into French depends on the context and your preference.