 Coombes went on to represent Munster at Under-18 and Under-19 levels, winning inter-provincial championships with both, as well as also representing Ireland at Under-18 and Under-19 levels.Coombes was part of the Munster A team that won the 2016–17 British and Irish Cup, with Coombes starting at blindside flanker in the 29–28 victory against Jersey Reds in the final on 21 April 2017.Coombes started at number 8 in both of Munster's pre-season friendlies in August 2018, before being named in his first Pro14 squad.