i figured it out

{athletes
        .filter((athlete) => {
          if (search === "") {
            return athlete;
          } else if (
            athlete.fullName.toLowerCase().includes(search.toLowerCase())
          ) {
            return athlete;
          }
        })

        .map((athlete, key) => (
          <AthleteCard
            key={key}
            athlete={athlete}
            selectedAthletes={athletesForm}
            updateAthletesForm={updateAthletesForm}
          />
        ))}