In online, you have much more powerful option "conditional moves"
You can define different answers for your opponent's possible moves. In case of forced lines, you can "program" 6-7 moves ahead (you can do so for non-forcing lines too, but less likely your opponent's play will match all the moves)
I did start a thread in "help & support" wondering about the premove option,-or more so the lack of a premove option-, in online correspondence chess. Since I did not get a response from chess.com staff I figured I should suggest it here in this forum.
It would be quite practical at times.
Either way thanks for a great site!