Barnes ayaa ku guuleystay billad dahab ah Mareykanka 2017 FIBA Under-16 Americas Championship ee Formosa, Argentina ka dib markii uu celcelis ahaan 9.8 dhibcood, 3.2 rebounds iyo 2.4 xaday ciyaar kasta. Guushii semi finalka ee Argentina, wuxuu hogaamiyay dhamaan goolhayaha oo leh 20 dhibcood iyo lix xaday isagoo jabiyay rikoodhka Mareykanka ee ka yar 16 sano ee boqolkiiba tuurista bilaashka ah isagoo toogtay 8 ka mid ah 8 khadka tuurka bilaashka ah. Koobkii Adduunka ee FIBA Under-17 ee 2018 ee Argentina, Barnes wuxuu celcelis ahaan helay 9.5 dhibcood iyo 5.8 rebounds ciyaar kasta wuxuuna ku guuleystay billad dahab ah. Wuxuu celcelis ahaan helay 9.7 dhibcood, 4.9 dib u soo celinta iyo 2.7 caawimaad ciyaar kasta 2019 FIBA Under-19 World Cup
wuxuu ku guuleystay billaddiisii saddexaad ee dahabka ee xulka Mareykanka.