A female was here sufficient, because the sin of one of those was less than the sin of the ruler, for whom a male was required, Leviticus 4:21.
Related Commentaries of Leviticus 4:28
Leviticus 4:28
28 Or if his sin, which he hath sinned, come to his knowledge: then he shall bring his offering, a kid of the goats, a female without blemish, for his sin which he hath sinned.