The highest combo you can get in the latest installment of the Tetris franchise, Tetris Effect. A Decahexatris is achieved by accumulating a 16 row combo when the mode Zone is active (which is activated when the
player fills up the meter by clearing lines, which then puts the
game in a state where the blocks are frozen in place until the
player decides to move them). Once the Zone meter goes down, it allows players to essentially clear 16 rows at once, beating the past highest row combo you could get which was
4.