That isn't something that can be set. Normally, if a move isn't made in a certain amount of time, the game is aborted. However, if an account has a history of aborts, the aborts start causing rating losses.
https://support.chess.com/customer/en/portal/articles/1444922-fair-play-policy
Today I wasn't there when one of my bullet games started and it was "abandoned" after some time (before my timer was over) and I lost the game and thus rating points.
However I have seen other games where my opponent wasn't there at the beginning but the game just "auto-aborted" after 15 seconds and he didn't lose the game and rating points.
How do I set it the same way so if I am not there when the game starts, the game auto-aborts in the same way and I don't lose rating points???