A breakout game, I believe, is a game in which you score 20 or more points. So for this trophy you need to have 2 games in a row where you personally score at least 20 points.
In previous NBA 2K games you also needed a teammate grade of B+, but I don't think it matters what your teammate grade is for this year's trophy (correct me if I'm wrong though).
As an indicator, I got the trophy after a game of 24pts and B teammate grade, followed by a game of 23pts with a C- teammate grade.