Chess.com already has this feature. It is called conditional move. You predict your opponent's moves and respond to it.
The support article below will guide you on how to make conditional moves.
https://support.chess.com/article/333-how-do-i-make-conditional-moves.
Hello
I am playing a tournament, that has a 3-day window per move. It would be great, that if you checked the player, and they only had 1 move, that you don't have to wait around for days, for them to make it. Just do the move.
Cheers
Pretty sure that won't be added. While one move may be forced a player could decide to use their time to look at the following positions as well. Forcing an auto move would take potential thinking time away from a member.
Though, if it was added, it would likely be a setting that a member could turn on on their side, so if they only had a forced move, it would make it. So it would only help on those that had it enabled.
However, as @Staerex mentioned, you could set up a conditional move with your reply to the forced move.
This request has come through our queue recently. I definitely understand the frustration on waiting on forced moves in daily games.
The side effect is making moves for users (many of which may not have even recognized their next moves are forced), can create a very confusing, and arguably even more frustrating experience for them.
I hope this helps 
Thanks Caleb for the response. I can see how it might be jarring to come back to a game that looked a lot different than when you left it.
I suggested this once. It would be called a "trigger move". When you have only one legal move you can enable the setting to automatically make the move for you, like a premise. If both players had this enabled, a chess game could play itself for a few moves at the end:
The entire sequence is forced. I wonder if such a case could be an example where it may be justified for one side to win despite losing on time, because they have no choice but to checkmate their opponent. I think FIDE considers this a draw, but an interesting question.
Perhaps a middle ground is allowing users to simply confirm a forced move without to have to return to the game. User logs on, next move is forced, prompt them to one-click confirm.
In live games we see users stall when they get into a forced/losing position. I wouldn't be surprised if that's common in daily games as well.
I'll explore this with our team. We would need to have an eval available to know the next move is forced, so I would need to see how this could work in practice.
Love the discussion!
Hello
I am playing a tournament, that has a 3-day window per move. It would be great, that if you checked the player, and they only had 1 move, that you don't have to wait around for days, for them to make it. Just do the move.
Cheers