[7] In 2021, Mathias completed a degree in Exercise and Sport Science at University of Wales Trinity Saint David, while pursuing his rugby career.

[9] Mathias signed a contract extension with the Scarlets on 20 April 2023, along with fellow prop Sam Wainwright.

[10] While attending Sir Thomas Picton School, Mathias was selected for Wales U18 on their tour to South Africa in 2017, starting against England and scoring a try in the win.

[12] Mathias made his debut on 12 August 2023, coming off the bench against England in the 2023 Rugby World Cup warm-up matches.

[13] Mathias was named in the Wales squad for the 2024 Six Nations Championship, and came off the bench in the final match against Italy.