Complex sentence: On the opening match against Bhutan, Magar opened the scoresheet with a goal, followed by 2 more, routing Bhutan 3:1 with a hat-trick on his U19 debut.
Split into simpler sentences: On the opening match against Bhutan, Magar opened the scoresheet with a goal, followed by 2 more, beating the Bhutanese 3:1. Thus, completing his hat-trick on his U19 debut.