Sforno on Genesis 37:3/ספורנו על בראשית ל״ז:ג׳

1ועשה לו כתונת פסים, as a visible sign that Joseph was intended by him to become the leader of all the brothers both at home and in the field. The use of such distinctive clothing to symbolise someone’s elevated stature is found also in Isaiah 22,21 והלבשתיו כתנתך, “I will dress him (Chilkiyah) in your tunic,” where it signals that authority is transferred to the one wearing the appropriate garments. (uniform). The Talmud Baba Kama 11 also confirms that authority is signalled by the attire worn by people possessing it. [there the brothers who had paid extra for their leader to represent them and to appear well dressed are quite content seeing that their representative while attired in costly garments will indirectly confer benefits upon them through their brother being listened to in the councils of the city. Ed.]