chess.com does actually have a feature for abandonment, so you don't always have to wait for the opponent's entire clock to run out. However, this only works up until move 10. How long they have before "abandoned" depends on the time control: https://support.chess.com/en/articles/8593801-how-does-game-abandonment-work
If they prolong the game unnecessarily, then you should report them for stalling. Not only is this poor sportsmanship to make you wait, but stalling is reportable. https://support.chess.com/en/articles/8562517-how-do-i-report-someone
Recently, I observed it while messing with my opponent's little mind they simply abandoned the game or sometimes resigns but there is no fun. It's sucky tbh. The moment you click on the play button you must be pretty confident to beat down your opponent till the last breath if you can't then why to abandon just learn his/her gameplay and improvise yours. Also, I request chess.com to take some strict actions against those [removed insult-- S19] minds. Either completely block them from playing chess at least on this platform or deduct their point to understand the true meaning of sportsmanship.🙏🏻 P.S. It's very frustrating your [removed insult-- S19] 0pp0nents make you burn your calories and leave the game when they are about to lose. If I was the coder behind the app I would have written a logic to block such [removed profanity-- S19].