I believe chess.com allows for slow games for as long as 120 minutes to a side.
Most real (Over-the-board or OTB) chess tournaments have time controls as " fast " as 30 minutes and as slow as 2-3 hours per side, so this option to play slow is not as shocking as you might think.
You'd be surprised how many of us believe that any chess played under a 30 minute time control is not ideal for serious play. For example, highly analytical positions (with tons of forcing variations to calculate) is a fantastic training ground to improve one's chess and you're just wasting it away if you force yourself to make a move in less than a minute.
What the longest you can opt for? Like 15 mins per player, so they call that a 30 min game? Just wondering if there is a twenty or thirty min time for each player game? I just cannot hack 15 min games but I am very impress at the quality some players can play even at 15mins!